Publications
Included in the list are the publications since 2011, authored by members of Department of Physics of Crystals and Department of Physics of Nanomaterials, which in 2019 merged into the Department of Physics of Nanostructures.
2024
350.
Bivas Rana
Role of voltage-controlled magnetic anisotropy in the recent development of magnonics and spintronics Journal Article
In: Journal of Applied Physics, vol. 136, no. 15, pp. 150701, 2024.
@article{10.1063/5.0233693,
title = {Role of voltage-controlled magnetic anisotropy in the recent development of magnonics and spintronics},
author = {Bivas Rana
},
url = {https://doi.org/10.1063/5.0233693},
doi = {10.1063/5.0233693},
year = {2024},
date = {2024-10-16},
journal = {Journal of Applied Physics},
volume = {136},
number = {15},
pages = {150701},
abstract = {With significant recent progress in the thin film deposition and nanofabrication technology, a number of physical phenomena occur at the interfaces of magnetic thin films, and their heterostructures have been discovered. Consequently, the electric field-induced modulation of those interfacial properties mediated through spin–orbit coupling promises to develop magnetic material based smarter, faster, miniaturized, energy efficient spintronic devices. Among them, the electric field-induced modification of interfacial magnetic anisotropy, popularly termed as voltage-controlled magnetic anisotropy (VCMA), has attracted special attention because of its salient features. This article is devoted to reviewing the recent development of magnonics, which deals with collective precessional motion of ordered magnetic spins, i.e., spin waves (SWs), and skyrmions with chiral spin textures, with VCMA, including the perspectives of this research field. Starting with a broad introduction, the key features of VCMA and its advantages over other electric field-induced methods are highlighted. These are followed by describing the state-of-the-art of VCMA, and various other direct and indirect electric field-induced methods for magnetization reversal; controlling skyrmion dynamics; excitation, manipulation, and channeling of SWs; and tailoring magnonic bands. The critical challenges, their possible solutions, and future perspectives of this field are thoroughly discussed throughout the article.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
With significant recent progress in the thin film deposition and nanofabrication technology, a number of physical phenomena occur at the interfaces of magnetic thin films, and their heterostructures have been discovered. Consequently, the electric field-induced modulation of those interfacial properties mediated through spin–orbit coupling promises to develop magnetic material based smarter, faster, miniaturized, energy efficient spintronic devices. Among them, the electric field-induced modification of interfacial magnetic anisotropy, popularly termed as voltage-controlled magnetic anisotropy (VCMA), has attracted special attention because of its salient features. This article is devoted to reviewing the recent development of magnonics, which deals with collective precessional motion of ordered magnetic spins, i.e., spin waves (SWs), and skyrmions with chiral spin textures, with VCMA, including the perspectives of this research field. Starting with a broad introduction, the key features of VCMA and its advantages over other electric field-induced methods are highlighted. These are followed by describing the state-of-the-art of VCMA, and various other direct and indirect electric field-induced methods for magnetization reversal; controlling skyrmion dynamics; excitation, manipulation, and channeling of SWs; and tailoring magnonic bands. The critical challenges, their possible solutions, and future perspectives of this field are thoroughly discussed throughout the article.
349.
Piotr Graczyk, M Pugaczowa-Michalska, Maciej Krawczyk
Generation of femtosecond spin-polarized current pulses at Fe/MgO interface by quasi-static voltage Journal Article
In: Physica E: Low-dimensional Systems and Nanostructures, vol. 165, pp. 116120, 2024, ISSN: 1386-9477.
@article{GRACZYK2025116120,
title = {Generation of femtosecond spin-polarized current pulses at Fe/MgO interface by quasi-static voltage},
author = {Piotr Graczyk and M Pugaczowa-Michalska and Maciej Krawczyk},
url = {https://www.sciencedirect.com/science/article/pii/S1386947724002248},
doi = {https://doi.org/10.1016/j.physe.2024.116120},
issn = {1386-9477},
year = {2024},
date = {2024-10-04},
journal = {Physica E: Low-dimensional Systems and Nanostructures},
volume = {165},
pages = {116120},
abstract = {The generation of short spin-current pulses is essential for fast spintronic devices. So far, spin current pulses are generated by femtosecond laser pulses which drive spins from a ferromagnetic metal layer. However, the need for miniaturization, simplicity and energy efficiency favour electric-field control of spintronic devices over optic or thermal control. Here, we combine ab initio calculations of electronic density of states at MgO/Fe interface with continuous model for charge transport to investigate the dynamics of the spin-dependent potential. We demonstrate that the voltage-driven instability of the electronic band structure due to the electronic resonant states at the Fe/MgO interface results in the generation of the femtosecond spin-polarized current pulse with the spin polarization up to P=7 00 % that propagates from the interface to the bulk. The dynamics of the current pulses driven by the Stoner instability depends neither on the dielectric relaxation time nor on the details of how the instability is achieved by changing the voltage, i.e. as long as the voltage changes are slow (quasi-static) with respect to the time determined by the spin diffusion constant, being of the order of fs. The presence of the instability can be detected by THz time-domain spectroscopy or pump-probe techniques.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The generation of short spin-current pulses is essential for fast spintronic devices. So far, spin current pulses are generated by femtosecond laser pulses which drive spins from a ferromagnetic metal layer. However, the need for miniaturization, simplicity and energy efficiency favour electric-field control of spintronic devices over optic or thermal control. Here, we combine ab initio calculations of electronic density of states at MgO/Fe interface with continuous model for charge transport to investigate the dynamics of the spin-dependent potential. We demonstrate that the voltage-driven instability of the electronic band structure due to the electronic resonant states at the Fe/MgO interface results in the generation of the femtosecond spin-polarized current pulse with the spin polarization up to P=7 00 % that propagates from the interface to the bulk. The dynamics of the current pulses driven by the Stoner instability depends neither on the dielectric relaxation time nor on the details of how the instability is achieved by changing the voltage, i.e. as long as the voltage changes are slow (quasi-static) with respect to the time determined by the spin diffusion constant, being of the order of fs. The presence of the instability can be detected by THz time-domain spectroscopy or pump-probe techniques.
348.
Sławomir Mamica
Spin-wave mode coupling in the presence of the demagnetizing field in cobalt-permalloy magnonic crystals Journal Article
In: Scientific Reports, vol. 14, iss. 1, pp. 22966, 2024.
@article{Mamica2024Spinwavemodecoupling,
title = {Spin-wave mode coupling in the presence of the demagnetizing field in cobalt-permalloy magnonic crystals},
author = {Sławomir Mamica},
url = {https://doi.org/10.1038/s41598-024-74923-2},
doi = {10.1038/s41598-024-74923-2},
year = {2024},
date = {2024-10-03},
journal = {Scientific Reports},
volume = {14},
issue = {1},
pages = {22966},
abstract = {We present the results of studies on the non-uniform frequency shift of spin wave spectrum in a two-dimensional magnonic crystal of cobalt/permalloy under the influence of external magnetic field changes. We investigate the phenomenon of coupling of modes and, as a consequence, their hybridization. By taking advantage of the fact that compressing the crystal structure along the direction of the external magnetic field leads to an enhancement of the demagnetizing field, we analyse its effect on the frequency shift of individual modes depending on their concentration in Co. We show that the consequence of this enhancement is a shift in the coupling of modes towards higher magnetic fields. This provides a potential opportunity to design which pairs of modes and in what range of fields hybridization will occur.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present the results of studies on the non-uniform frequency shift of spin wave spectrum in a two-dimensional magnonic crystal of cobalt/permalloy under the influence of external magnetic field changes. We investigate the phenomenon of coupling of modes and, as a consequence, their hybridization. By taking advantage of the fact that compressing the crystal structure along the direction of the external magnetic field leads to an enhancement of the demagnetizing field, we analyse its effect on the frequency shift of individual modes depending on their concentration in Co. We show that the consequence of this enhancement is a shift in the coupling of modes towards higher magnetic fields. This provides a potential opportunity to design which pairs of modes and in what range of fields hybridization will occur.
347.
Shashank Shekhar, Sławomir Mielcarek, Y Otani, Bivas Rana, Aleksandra Trzaskowska
Effect of the underlayer on the elastic parameters of the CoFeB/MgO heterostructures Journal Article
In: Scientific Reports, vol. 14, iss. 1, pp. 20259, 2024.
@article{Shekhar2024Effect,
title = {Effect of the underlayer on the elastic parameters of the CoFeB/MgO heterostructures},
author = {Shashank Shekhar and Sławomir Mielcarek and Y Otani and Bivas Rana and Aleksandra Trzaskowska},
url = {https://doi.org/10.1038/s41598-024-71110-1},
doi = {10.1038/s41598-024-71110-1},
year = {2024},
date = {2024-08-31},
urldate = {2024-08-31},
journal = {Scientific Reports},
volume = {14},
issue = {1},
pages = {20259},
abstract = {We investigated the thermally induced surface acoustic waves in CoFeB/MgO heterostructures with different underlayer materials. Our results show a direct correlation between the density and elastic parameters of the underlayer materials and the surface phonon dispersion. Using finite element method-based simulations, we calculate the effective elastic parameters (such as elastic tensor, Young’s modulus, and Poisson’s ratio) for multilayers with different underlayer materials. The simulation results, either considering the elastic parameters of individual layers or considering the effective elastic parameters of whole stacks, exhibit good agreement with the experimental data. This study will help us deepen our understanding of phonon properties and their interactions with other quasiparticles or magnetic textures with the help of these estimated elastic properties.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We investigated the thermally induced surface acoustic waves in CoFeB/MgO heterostructures with different underlayer materials. Our results show a direct correlation between the density and elastic parameters of the underlayer materials and the surface phonon dispersion. Using finite element method-based simulations, we calculate the effective elastic parameters (such as elastic tensor, Young’s modulus, and Poisson’s ratio) for multilayers with different underlayer materials. The simulation results, either considering the elastic parameters of individual layers or considering the effective elastic parameters of whole stacks, exhibit good agreement with the experimental data. This study will help us deepen our understanding of phonon properties and their interactions with other quasiparticles or magnetic textures with the help of these estimated elastic properties.
346.
R Mehta, Bivas Rana, S Saha
Magnetization dynamics in quasiperiodic magnonic crystals Journal Article
In: Journal of Physics: Condensed Matter, vol. 36 , no. 44, pp. 443003, 2024.
@article{Mehta2024,
title = {Magnetization dynamics in quasiperiodic magnonic crystals},
author = {R Mehta and Bivas Rana and S Saha},
doi = {10.1088/1361-648X/ad5ee8},
year = {2024},
date = {2024-08-08},
journal = {Journal of Physics: Condensed Matter},
volume = {36 },
number = {44},
pages = {443003},
abstract = {Quasiperiodic magnonic crystals, in contrast to their periodic counterparts, lack strict periodicity which gives rise to complex and localised spin wave spectra characterized by numerous band gaps and fractal features. Despite their intrinsic structural complexity, quasiperiodic nature of these magnonic crystals enables better tunability of spin wave spectra over their periodic counterparts and therefore holds promise for the applications in reprogrammable magnonic devices. In this article, we provide an overview of magnetization reversal and precessional magnetization dynamics studied so far in various quasiperiodic magnonic crystals, illustrating how their quasiperiodic nature gives rise to tailored band structure, enabling unparalleled control over spin waves. The review is concluded by highlighting the possible potential applications of these quasiperiodic magnonic crystals, exploring potential avenues for future exploration followed by a brief summary.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Quasiperiodic magnonic crystals, in contrast to their periodic counterparts, lack strict periodicity which gives rise to complex and localised spin wave spectra characterized by numerous band gaps and fractal features. Despite their intrinsic structural complexity, quasiperiodic nature of these magnonic crystals enables better tunability of spin wave spectra over their periodic counterparts and therefore holds promise for the applications in reprogrammable magnonic devices. In this article, we provide an overview of magnetization reversal and precessional magnetization dynamics studied so far in various quasiperiodic magnonic crystals, illustrating how their quasiperiodic nature gives rise to tailored band structure, enabling unparalleled control over spin waves. The review is concluded by highlighting the possible potential applications of these quasiperiodic magnonic crystals, exploring potential avenues for future exploration followed by a brief summary.
345.
A Girich, Liubov Ivzhenko, G Kharchenko, S Polevoy, S Tarapov, Maciej Krawczyk, Jarosław W Kłos
Existence of edge modes in periodic microstrip transmission line Journal Article
In: Scientific Reports, vol. 14, no. 16477, 2024.
@article{Ivzhenko_2024,
title = {Existence of edge modes in periodic microstrip transmission line},
author = {A Girich and Liubov Ivzhenko and G Kharchenko and S Polevoy and S Tarapov and Maciej Krawczyk and Jarosław W Kłos},
url = {https://doi.org/10.1038/s41598-024-67610-9
},
year = {2024},
date = {2024-07-16},
urldate = {2024-07-16},
journal = {Scientific Reports},
volume = {14},
number = {16477},
abstract = {The microstrip of modulated width is a realization of a one-dimensional photonic crystal operating in the microwave regime. Like any photonic crystal, the periodic microstrip is characterised by the presence of frequency bands and band gaps that enable and prohibit wave propagation, respectively. The frequency bands for microstrip of the symmetric unit cell can be distinguished by 0 or pi Zak phase. The sum of these topological parameters for all bands below a given frequency gap determines the value of the surface impedance at the end of the microstrip. We demonstrate that edge modes are absent in a finite microstrip terminated at both ends in the centres of unit cells, but they can be induced by adding the defected cells. Edge modes present at both ends of the microstrip enable microwave tunneling with high transitivity in the frequency gap with or without a change in phase. This has been demonstrated experimentally and developed in detail using numerical simulations and model calculations. The investigated system, with a doublet of edge modes in the frequency gap, can be considered as a narrow passband filter of high selectivity and characterised by a significant group delay.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The microstrip of modulated width is a realization of a one-dimensional photonic crystal operating in the microwave regime. Like any photonic crystal, the periodic microstrip is characterised by the presence of frequency bands and band gaps that enable and prohibit wave propagation, respectively. The frequency bands for microstrip of the symmetric unit cell can be distinguished by 0 or pi Zak phase. The sum of these topological parameters for all bands below a given frequency gap determines the value of the surface impedance at the end of the microstrip. We demonstrate that edge modes are absent in a finite microstrip terminated at both ends in the centres of unit cells, but they can be induced by adding the defected cells. Edge modes present at both ends of the microstrip enable microwave tunneling with high transitivity in the frequency gap with or without a change in phase. This has been demonstrated experimentally and developed in detail using numerical simulations and model calculations. The investigated system, with a doublet of edge modes in the frequency gap, can be considered as a narrow passband filter of high selectivity and characterised by a significant group delay.
344.
Miłosz Zdunek, Shashank Shekhar, Sławomir Mielcarek, Aleksandra Trzaskowska
Investigation of phonons and magnons in [Ni80Fe20/Au/Co/Au]N multilayers Journal Article
In: Journal of Physics: Condensed Matter, vol. 36, no. 37, pp. 375801, 2024.
@article{zdunek_multilayers,
title = {Investigation of phonons and magnons in [Ni80Fe20/Au/Co/Au]N multilayers},
author = {Miłosz Zdunek and Shashank Shekhar and Sławomir Mielcarek and Aleksandra Trzaskowska},
doi = {10.1088/1361-648X/ad5486},
year = {2024},
date = {2024-06-18},
journal = {Journal of Physics: Condensed Matter},
volume = {36},
number = {37},
pages = {375801},
abstract = {The interaction between phonons and magnons is a rapidly developing area of research, particularly in the field of acoustic spintronics. To discuss this interaction, it is necessary to observe two different waves (acoustic and spin waves) with the same frequency and wavelength. In the Ni80Fe20/Au/Co/Au system deposited on a silicon substrate, we observe the interaction between spin waves and surface acoustic waves using Brillouin light scattering spectroscopy. As a result, we can selectively control (activate or deactivate) the magnetoelastic interaction between the fundamental spin wave mode and surface acoustic waves. This is achieved by adjusting the magnetostrictive layer thickness in the multilayer. We demonstrate that by adjusting the number of layers in a multilayer structure, it is possible to precisely control the dispersion of surface acoustic waves while having minimal impact on the fundamental spin wave mode.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interaction between phonons and magnons is a rapidly developing area of research, particularly in the field of acoustic spintronics. To discuss this interaction, it is necessary to observe two different waves (acoustic and spin waves) with the same frequency and wavelength. In the Ni80Fe20/Au/Co/Au system deposited on a silicon substrate, we observe the interaction between spin waves and surface acoustic waves using Brillouin light scattering spectroscopy. As a result, we can selectively control (activate or deactivate) the magnetoelastic interaction between the fundamental spin wave mode and surface acoustic waves. This is achieved by adjusting the magnetostrictive layer thickness in the multilayer. We demonstrate that by adjusting the number of layers in a multilayer structure, it is possible to precisely control the dispersion of surface acoustic waves while having minimal impact on the fundamental spin wave mode.
343.
B Flebus, D Grundler, Bivas Rana, Y Otani, I Barsukov, A Barman, G Gubbiotti, P Landeros, J Akerman, U Ebels, P Pirro, V E Demidov, K Schultheiss, G Csaba, Q Wang, F Ciubotaru, D E Nikonov, P Che, R Hertel, T Ono, D Afanasiev, J Mentink, T Rasing, B Hillebrands, S V Kusminskiy, W Zhang, C R Du, A Finco, T van der Sar, Y K Luo, Y Shiota, J Sklenar, T Yu, J Rao
The 2024 magnonics roadmap Journal Article
In: Journal of Physics: Condensed Matter, vol. 36, no. 36, pp. 363501, 2024.
@article{Flebus_2024,
title = {The 2024 magnonics roadmap},
author = {B Flebus and D Grundler and Bivas Rana and Y Otani and I Barsukov and A Barman and G Gubbiotti and P Landeros and J Akerman and U Ebels and P Pirro and V E Demidov and K Schultheiss and G Csaba and Q Wang and F Ciubotaru and D E Nikonov and P Che and R Hertel and T Ono and D Afanasiev and J Mentink and T Rasing and B Hillebrands and S V Kusminskiy and W Zhang and C R Du and A Finco and T van der Sar and Y K Luo and Y Shiota and J Sklenar and T Yu and J Rao},
url = {https://dx.doi.org/10.1088/1361-648X/ad399c},
doi = {10.1088/1361-648X/ad399c},
year = {2024},
date = {2024-06-14},
urldate = {2024-06-14},
journal = {Journal of Physics: Condensed Matter},
volume = {36},
number = {36},
pages = {363501},
abstract = {Magnonics is a research field that has gained an increasing interest in both the fundamental and applied sciences in recent years. This field aims to explore and functionalize collective spin excitations in magnetically ordered materials for modern information technologies, sensing applications and advanced computational schemes. Spin waves, also known as magnons, carry spin angular momenta that allow for the transmission, storage and processing of information without moving charges. In integrated circuits, magnons enable on-chip data processing at ultrahigh frequencies without the Joule heating, which currently limits clock frequencies in conventional data processors to a few GHz. Recent developments in the field indicate that functional magnonic building blocks for in-memory computation, neural networks and Ising machines are within reach. At the same time, the miniaturization of magnonic circuits advances continuously as the synergy of materials science, electrical engineering and nanotechnology allows for novel on-chip excitation and detection schemes. Such circuits can already enable magnon wavelengths of 50 nm at microwave frequencies in a 5G frequency band. Research into non-charge-based technologies is urgently needed in view of the rapid growth of machine learning and artificial intelligence applications, which consume substantial energy when implemented on conventional data processing units. In its first part, the 2024 Magnonics Roadmap provides an update on the recent developments and achievements in the field of nano-magnonics while defining its future avenues and challenges. In its second part, the Roadmap addresses the rapidly growing research endeavors on hybrid structures and magnonics-enabled quantum engineering. We anticipate that these directions will continue to attract researchers to the field and, in addition to showcasing intriguing science, will enable unprecedented functionalities that enhance the efficiency of alternative information technologies and computational schemes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Magnonics is a research field that has gained an increasing interest in both the fundamental and applied sciences in recent years. This field aims to explore and functionalize collective spin excitations in magnetically ordered materials for modern information technologies, sensing applications and advanced computational schemes. Spin waves, also known as magnons, carry spin angular momenta that allow for the transmission, storage and processing of information without moving charges. In integrated circuits, magnons enable on-chip data processing at ultrahigh frequencies without the Joule heating, which currently limits clock frequencies in conventional data processors to a few GHz. Recent developments in the field indicate that functional magnonic building blocks for in-memory computation, neural networks and Ising machines are within reach. At the same time, the miniaturization of magnonic circuits advances continuously as the synergy of materials science, electrical engineering and nanotechnology allows for novel on-chip excitation and detection schemes. Such circuits can already enable magnon wavelengths of 50 nm at microwave frequencies in a 5G frequency band. Research into non-charge-based technologies is urgently needed in view of the rapid growth of machine learning and artificial intelligence applications, which consume substantial energy when implemented on conventional data processing units. In its first part, the 2024 Magnonics Roadmap provides an update on the recent developments and achievements in the field of nano-magnonics while defining its future avenues and challenges. In its second part, the Roadmap addresses the rapidly growing research endeavors on hybrid structures and magnonics-enabled quantum engineering. We anticipate that these directions will continue to attract researchers to the field and, in addition to showcasing intriguing science, will enable unprecedented functionalities that enhance the efficiency of alternative information technologies and computational schemes.
342.
M Gokkavas, T F Gundogdu, E Ozbay, Andriy E Serebryannikov
Few-layer bifunctional metasurfaces enabling asymmetric and symmetric polarization-plane rotation at the subwavelength scale Journal Article
In: Scientific Reports, vol. 14, iss. 1, pp. 13636, 2024.
@article{Serebryannikov_Few_layer_bifunctional,
title = {Few-layer bifunctional metasurfaces enabling asymmetric and symmetric polarization-plane rotation at the subwavelength scale},
author = {M Gokkavas and T F Gundogdu and E Ozbay and Andriy E Serebryannikov},
url = {https://doi.org/10.1038/s41598-024-62073-4
},
doi = {10.1038/s41598-024-62073-4},
year = {2024},
date = {2024-06-13},
journal = {Scientific Reports},
volume = {14},
issue = {1},
pages = {13636},
abstract = {We introduce and numerically validate the concept of few-layer bifunctional metasurfaces comprising two arrays of quasiplanar subwavelength resonators and a middle grid (array of rectangular holes) that offer both symmetric and asymmetric transmissions connected, respectively, with symmetric and asymmetric polarization-plane rotation functionalities. The proposed structures are thinner than $$lambda /7$$and free of diffractions. Usually, the structure’s symmetry or asymmetry, i.e. unbroken or broken spatial inversion symmetries, are considered for metasurfaces as prerequisites of the capability of symmetric or asymmetric conversion of linearly polarized waves, respectively. Due to the achieved adjustment of the resonances enabling the rotation of the polarization plane simultaneously for both orthogonal polarizations of the incident wave, the symmetric polarization-plane rotation functionality can be obtained within one subwavelength band, whereas the asymmetric polarization-plane rotation functionality associated with the asymmetric transmission is obtained within another subwavelength band. This combination of the functionalities in one subdiffraction structure is possible due to the optimal choice of the grid parameters, since they may strongly affect the coupling between the two resonator arrays. Although normal incidence is required for the targeted bifunctionality, the variations of the incidence angle can also be exploited for the enrichment of the overall functional capability. Variations of the polarization angle give another important degree of freedom. The connection between the polarization-angle dependence of cross-polarized transmission and capability of symmetric and asymmetric polarization-plane rotation functionalities is highlighted. The feasible designs of the bifunctional metasurfaces are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We introduce and numerically validate the concept of few-layer bifunctional metasurfaces comprising two arrays of quasiplanar subwavelength resonators and a middle grid (array of rectangular holes) that offer both symmetric and asymmetric transmissions connected, respectively, with symmetric and asymmetric polarization-plane rotation functionalities. The proposed structures are thinner than $$lambda /7$$and free of diffractions. Usually, the structure’s symmetry or asymmetry, i.e. unbroken or broken spatial inversion symmetries, are considered for metasurfaces as prerequisites of the capability of symmetric or asymmetric conversion of linearly polarized waves, respectively. Due to the achieved adjustment of the resonances enabling the rotation of the polarization plane simultaneously for both orthogonal polarizations of the incident wave, the symmetric polarization-plane rotation functionality can be obtained within one subwavelength band, whereas the asymmetric polarization-plane rotation functionality associated with the asymmetric transmission is obtained within another subwavelength band. This combination of the functionalities in one subdiffraction structure is possible due to the optimal choice of the grid parameters, since they may strongly affect the coupling between the two resonator arrays. Although normal incidence is required for the targeted bifunctionality, the variations of the incidence angle can also be exploited for the enrichment of the overall functional capability. Variations of the polarization angle give another important degree of freedom. The connection between the polarization-angle dependence of cross-polarized transmission and capability of symmetric and asymmetric polarization-plane rotation functionalities is highlighted. The feasible designs of the bifunctional metasurfaces are discussed.
341.
Julia Kharlan, Krzysztof Sobucki, Krzysztof Szulc, Sara Memarzadeh, Jarosław W Kłos
Spin-wave confinement in a hybrid superconductor-ferrimagnet nanostructure Journal Article
In: Phys. Rev. Appl., vol. 21, iss. 6, no. 16, pp. 064007, 2024.
@article{PhysRevApplied.21.064007,
title = {Spin-wave confinement in a hybrid superconductor-ferrimagnet nanostructure},
author = {Julia Kharlan and Krzysztof Sobucki and Krzysztof Szulc and Sara Memarzadeh and Jarosław W Kłos},
url = {https://doi.org/10.1103/PhysRevApplied.21.064007},
doi = {10.1103/PhysRevApplied.21.064007},
year = {2024},
date = {2024-06-05},
urldate = {2024-06-05},
journal = {Phys. Rev. Appl.},
volume = {21},
number = {16},
issue = {6},
pages = {064007},
abstract = {Eddy currents in a superconductor shield the magnetic field in its interior and are responsible for the formation of a magnetic stray field outside of the superconducting structure. The stray field can be controlled by the external magnetic field and affect the magnetization dynamics in the magnetic system placed in its range. In the case of a hybrid system consisting of a superconducting strip placed over a magnetic layer, we theoretically predict the confinement of spin waves in the well of the static stray field. The number of bound states and their frequencies can be controlled by an external magnetic field. We present the results of semianalytical calculations complemented by numerical modeling.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Eddy currents in a superconductor shield the magnetic field in its interior and are responsible for the formation of a magnetic stray field outside of the superconducting structure. The stray field can be controlled by the external magnetic field and affect the magnetization dynamics in the magnetic system placed in its range. In the case of a hybrid system consisting of a superconducting strip placed over a magnetic layer, we theoretically predict the confinement of spin waves in the well of the static stray field. The number of bound states and their frequencies can be controlled by an external magnetic field. We present the results of semianalytical calculations complemented by numerical modeling.
340.
W Andrzejewska, P Wojciechowski, M V Dobrotvorska, S Murawka, P Sobieszczyk, Mateusz Zelent, M Lewandowski
Directional growth of iron oxide nanowires on a vicinal copper surface Journal Article
In: Journal of Physics: Condensed Matter, vol. 36, no. 34, pp. 345004, 2024.
@article{Andrzejewska_Directional_growth,
title = {Directional growth of iron oxide nanowires on a vicinal copper surface},
author = {W Andrzejewska and P Wojciechowski and M V Dobrotvorska and S Murawka and P Sobieszczyk and Mateusz Zelent and M Lewandowski},
doi = {10.1088/1361-648X/ad3e58},
year = {2024},
date = {2024-05-30},
journal = {Journal of Physics: Condensed Matter},
volume = {36},
number = {34},
pages = {345004},
abstract = {Single-crystal magnetic nanostructures with well-defined shapes attract lots of interest due to their potential applications in magnetic and spintronic devices. However, development of methods allowing controlling their mutual crystallographic and geometric orientation constitutes a significant scientific challenge. One of the routes for obtaining such structures is to grow the materials epitaxially on naturally-structured supports, such as vicinal surfaces of single-crystal substrates. Iron oxides are among the most well-known magnetic materials which, depending on the phase, may exhibit ferro/ferri- or antiferromagnetic ordering. We have grown iron oxide nanowires on a Cu(410) single-crystal substrate faceted with molecular oxygen. Scanning tunneling microscopy and low energy electron diffraction revealed that the oxide grows in the [111] direction, along the step edges of the substrate and rotated by ±15° with respect to the [010] direction of copper atomic terraces (so that the the growing elongated structures are orientated parallel to each other). Notably, x-ray photoelectron spectroscopy confirmed that the nanowires represent the ferrimagnetic γ-Fe2O3 (maghemite) iron oxide phase, while micromagnetic simulations indicated that the wires are single-domain, with the easy magnetization axis orientated in-plane and along the long axis of the wire.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Single-crystal magnetic nanostructures with well-defined shapes attract lots of interest due to their potential applications in magnetic and spintronic devices. However, development of methods allowing controlling their mutual crystallographic and geometric orientation constitutes a significant scientific challenge. One of the routes for obtaining such structures is to grow the materials epitaxially on naturally-structured supports, such as vicinal surfaces of single-crystal substrates. Iron oxides are among the most well-known magnetic materials which, depending on the phase, may exhibit ferro/ferri- or antiferromagnetic ordering. We have grown iron oxide nanowires on a Cu(410) single-crystal substrate faceted with molecular oxygen. Scanning tunneling microscopy and low energy electron diffraction revealed that the oxide grows in the [111] direction, along the step edges of the substrate and rotated by ±15° with respect to the [010] direction of copper atomic terraces (so that the the growing elongated structures are orientated parallel to each other). Notably, x-ray photoelectron spectroscopy confirmed that the nanowires represent the ferrimagnetic γ-Fe2O3 (maghemite) iron oxide phase, while micromagnetic simulations indicated that the wires are single-domain, with the easy magnetization axis orientated in-plane and along the long axis of the wire.
339.
Mathieu Moalic, Mateusz Zelent, Krzysztof Szulc, Maciej Krawczyk
The role of non-uniform magnetization texture for magnon–magnon coupling in an antidot lattice Journal Article
In: Scientific Reports, vol. 14, iss. 1, pp. 11501, 2024.
@article{moalic2024exploration,
title = {The role of non-uniform magnetization texture for magnon–magnon coupling in an antidot lattice},
author = {Mathieu Moalic and Mateusz Zelent and Krzysztof Szulc and Maciej Krawczyk},
url = {https://doi.org/10.1038/s41598-024-61246-5
},
doi = {10.1038/s41598-024-61246-5},
year = {2024},
date = {2024-05-20},
journal = {Scientific Reports},
volume = {14},
issue = {1},
pages = {11501},
abstract = {We numerically study the spin-wave dynamics in an antidot lattice based on a Co/Pd multilayer structure with reduced perpendicular magnetic anisotropy at the edges of the antidots. This structure forms a magnonic crystal with a periodic antidot pattern and a periodic magnetization configuration consisting of out-of-plane magnetized bulk and in-plane magnetized rims. Our results show a different behavior of spin waves in the bulk and in the rims under varying out-of-plane external magnetic field strength, revealing complex spin-wave spectra and hybridizations between the modes of these two subsystems. A particularly strong magnon–magnon coupling, due to exchange interactions, is found between the fundamental bulk spin-wave mode and the second-order radial rim modes. However, the dynamical coupling between the spin-wave modes at low frequencies, involving the first-order radial rim modes, is masked by the changes in the static magnetization at the bulk–rim interface with magnetic field changes. The study expands the horizons of magnonic-crystal research by combining periodic structural patterning and non-collinear magnetization texture to achieve strong magnon–magnon coupling, highlighting the significant role of exchange interactions in the hybridization.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We numerically study the spin-wave dynamics in an antidot lattice based on a Co/Pd multilayer structure with reduced perpendicular magnetic anisotropy at the edges of the antidots. This structure forms a magnonic crystal with a periodic antidot pattern and a periodic magnetization configuration consisting of out-of-plane magnetized bulk and in-plane magnetized rims. Our results show a different behavior of spin waves in the bulk and in the rims under varying out-of-plane external magnetic field strength, revealing complex spin-wave spectra and hybridizations between the modes of these two subsystems. A particularly strong magnon–magnon coupling, due to exchange interactions, is found between the fundamental bulk spin-wave mode and the second-order radial rim modes. However, the dynamical coupling between the spin-wave modes at low frequencies, involving the first-order radial rim modes, is masked by the changes in the static magnetization at the bulk–rim interface with magnetic field changes. The study expands the horizons of magnonic-crystal research by combining periodic structural patterning and non-collinear magnetization texture to achieve strong magnon–magnon coupling, highlighting the significant role of exchange interactions in the hybridization.
338.
Mateusz Gołębiewski, R Hertel, M d’Aquino, V I Vasyuchka, M Weiler, P Pirro, Maciej Krawczyk, S Fukami, H Ohno, J Llandro
Collective Spin-Wave Dynamics in Gyroid Ferromagnetic Nanostructures Journal Article
In: ACS Applied Materials & Interfaces, vol. 0, iss. 0, pp. 0, 2024.
@article{doi:10.1021/acsami.4c02366,,
title = {Collective Spin-Wave Dynamics in Gyroid Ferromagnetic Nanostructures},
author = {Mateusz Gołębiewski and R Hertel and M d’Aquino and V I Vasyuchka and M Weiler and P Pirro and Maciej Krawczyk and S Fukami and H Ohno and J Llandro},
url = {https://doi.org/10.1021/acsami.4c02366},
doi = {10.1021/acsami.4c02366},
year = {2024},
date = {2024-04-22},
urldate = {2024-04-22},
journal = {ACS Applied Materials & Interfaces},
volume = {0},
issue = {0},
pages = {0},
abstract = {Expanding upon the burgeoning discipline of magnonics, this research elucidates the intricate dynamics of spin waves (SWs) within three-dimensional nanoenvironments. It marks a shift from traditionally used planar systems to exploration of magnetization configurations and the resulting dynamics within 3D nanostructures. This study deploys micromagnetic simulations alongside ferromagnetic resonance measurements to scrutinize magnetic gyroids, periodic chiral configurations composed of chiral triple junctions with a period in nanoscale. Our findings uncover distinctive attributes intrinsic to the gyroid network, most notably the localization of collective SW excitations and the sensitivity of the gyroid’s ferromagnetic response to the orientation of the static magnetic field, a correlation closely tied to the crystallographic alignment of the structure. Furthermore, we show that for the ferromagnetic resonance, multidomain gyroid films can be treated as a magnonic material with effective magnetization scaled by its filling factor. The implications of our research carry the potential for practical uses such as an effective, metamaterial-like substitute for ferromagnetic parts and lay the groundwork for radio frequency filters. The growing areas of 3D magnonics and spintronics present exciting opportunities to investigate and utilize gyroid nanostructures for signal processing purposes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Expanding upon the burgeoning discipline of magnonics, this research elucidates the intricate dynamics of spin waves (SWs) within three-dimensional nanoenvironments. It marks a shift from traditionally used planar systems to exploration of magnetization configurations and the resulting dynamics within 3D nanostructures. This study deploys micromagnetic simulations alongside ferromagnetic resonance measurements to scrutinize magnetic gyroids, periodic chiral configurations composed of chiral triple junctions with a period in nanoscale. Our findings uncover distinctive attributes intrinsic to the gyroid network, most notably the localization of collective SW excitations and the sensitivity of the gyroid’s ferromagnetic response to the orientation of the static magnetic field, a correlation closely tied to the crystallographic alignment of the structure. Furthermore, we show that for the ferromagnetic resonance, multidomain gyroid films can be treated as a magnonic material with effective magnetization scaled by its filling factor. The implications of our research carry the potential for practical uses such as an effective, metamaterial-like substitute for ferromagnetic parts and lay the groundwork for radio frequency filters. The growing areas of 3D magnonics and spintronics present exciting opportunities to investigate and utilize gyroid nanostructures for signal processing purposes.
337.
N Kumar, Paweł Gruszecki, Mateusz Gołębiewski, Jarosław W Kłos, Maciej Krawczyk
Exciting High-Frequency Short-Wavelength Spin Waves using High Harmonics of a Magnonic Cavity Mode-Revision Journal Article
In: Advanced Quantum Technologies, pp. 2400015, 2024.
@article{https://doi.org/10.1002/qute.202400015,
title = {Exciting High-Frequency Short-Wavelength Spin Waves using High Harmonics of a Magnonic Cavity Mode-Revision},
author = {N Kumar and Paweł Gruszecki and Mateusz Gołębiewski and Jarosław W Kłos and Maciej Krawczyk},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/qute.202400015},
doi = {https://doi.org/10.1002/qute.202400015},
year = {2024},
date = {2024-03-29},
urldate = {2024-03-29},
journal = {Advanced Quantum Technologies},
pages = {2400015},
abstract = {Abstract Spin waves (SWs) are promising objects for signal processing and future quantum technologies due to their high microwave frequencies with corresponding nanoscale wavelengths. However, the nano-wavelength SWs generated so far are limited to low frequencies. In the paper, using micromagnetic simulations, it is shown that a microwave-pumped SW mode confined to the cavity of a thin film magnonic crystal (MC) can be used to generate waves at tens of GHz and wavelengths well below 50 nm. These multi-frequency harmonics of the fundamental cavity mode are generated when the amplitude of the pumping microwave field exceeds a threshold, and their intensities then scale linearly with the field intensity. The frequency of the cavity mode is equal to the ferromagnetic resonance frequency of the planar ferromagnetic film, which overlaps with the magnonic bandgap, providing an efficient mechanism for confinement and magnetic field tunability. The effect reaches saturation when the microstrip feed line covers the entire cavity, making the system feasible for realization.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Spin waves (SWs) are promising objects for signal processing and future quantum technologies due to their high microwave frequencies with corresponding nanoscale wavelengths. However, the nano-wavelength SWs generated so far are limited to low frequencies. In the paper, using micromagnetic simulations, it is shown that a microwave-pumped SW mode confined to the cavity of a thin film magnonic crystal (MC) can be used to generate waves at tens of GHz and wavelengths well below 50 nm. These multi-frequency harmonics of the fundamental cavity mode are generated when the amplitude of the pumping microwave field exceeds a threshold, and their intensities then scale linearly with the field intensity. The frequency of the cavity mode is equal to the ferromagnetic resonance frequency of the planar ferromagnetic film, which overlaps with the magnonic bandgap, providing an efficient mechanism for confinement and magnetic field tunability. The effect reaches saturation when the microstrip feed line covers the entire cavity, making the system feasible for realization.
336.
Krzysztof Szulc, Julia Kharlan, P Bondarenko, Elena Tartakovskaya, Maciej Krawczyk
Impact of surface anisotropy on the spin-wave dynamics in a thin ferromagnetic film Journal Article
In: Phys. Rev. B, vol. 109, iss. 5, pp. 054430, 2024.
@article{PhysRevB.109.054430,,
title = {Impact of surface anisotropy on the spin-wave dynamics in a thin ferromagnetic film},
author = {Krzysztof Szulc and Julia Kharlan and P Bondarenko and Elena Tartakovskaya and Maciej Krawczyk
},
doi = {10.1103/PhysRevB.109.054430},
year = {2024},
date = {2024-02-26},
journal = {Phys. Rev. B},
volume = {109},
issue = {5},
pages = {054430},
abstract = {The spin-wave dynamics in the thin CoFeB film in Damon-Eshbach geometry are studied in three cases of boundary conditions—free boundary conditions, symmetrical surface anisotropy, and one-sided surface anisotropy. The analytical model created by Wolfram and De Wames was extended to include perpendicular surface anisotropy in boundary conditions. Its comparison with numerical simulations demonstrates perfect agreement between the approaches. The analysis of the dispersion relation indicates that the presence of surface anisotropy increases the avoided crossing size between the Damon-Eshbach mode and perpendicular standing modes. Additionally, asymmetrical one-sided surface anisotropy induces nonreciprocity in the dispersion relation. In-depth analysis of the avoided crossing size is conducted for systems with different boundary conditions, different thicknesses, surface anisotropy constant values, and external magnetic fields. It shows the significant role of the strength of surface localization of the Damon-Eshbach mode and the symmetry of perpendicular standing modes in the avoided crossing broadening. Interestingly, for a specific set of parameters, the interaction between the particular modes can be suppressed, resulting in a mode crossing. Such a crossing, which occurs only for one direction of the wave vector in a one-sided surface anisotropy system, can be utilized in nonreciprocal devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The spin-wave dynamics in the thin CoFeB film in Damon-Eshbach geometry are studied in three cases of boundary conditions—free boundary conditions, symmetrical surface anisotropy, and one-sided surface anisotropy. The analytical model created by Wolfram and De Wames was extended to include perpendicular surface anisotropy in boundary conditions. Its comparison with numerical simulations demonstrates perfect agreement between the approaches. The analysis of the dispersion relation indicates that the presence of surface anisotropy increases the avoided crossing size between the Damon-Eshbach mode and perpendicular standing modes. Additionally, asymmetrical one-sided surface anisotropy induces nonreciprocity in the dispersion relation. In-depth analysis of the avoided crossing size is conducted for systems with different boundary conditions, different thicknesses, surface anisotropy constant values, and external magnetic fields. It shows the significant role of the strength of surface localization of the Damon-Eshbach mode and the symmetry of perpendicular standing modes in the avoided crossing broadening. Interestingly, for a specific set of parameters, the interaction between the particular modes can be suppressed, resulting in a mode crossing. Such a crossing, which occurs only for one direction of the wave vector in a one-sided surface anisotropy system, can be utilized in nonreciprocal devices.
335.
Andriy E Serebryannikov, A Lakhtakia, E Ozbay
Thermally mediated transmission-mode deflection of terahertz waves by lamellar metagratings containing a phase-change material Journal Article
In: Opt. Mater. Express, vol. 14, no. 3, pp. 745–758, 2024.
@article{Serebryannikov:24,
title = {Thermally mediated transmission-mode deflection of terahertz waves by lamellar metagratings containing a phase-change material},
author = {Andriy E Serebryannikov and A Lakhtakia and E Ozbay},
url = {https://opg.optica.org/ome/abstract.cfm?URI=ome-14-3-745},
doi = {10.1364/OME.511804},
year = {2024},
date = {2024-02-15},
journal = {Opt. Mater. Express},
volume = {14},
number = {3},
pages = {745--758},
abstract = {The planewave-response characteristics of simple lamellar metagratings exhibiting thermally mediated transmission-mode deflection (blazing) were numerically investigated, the unit cell of each metagrating containing a phase-change material chosen to be indium antimonide (InSb). Thermal control arises from the use of InSb in its insulator phase and the vicinity of the vacuum state. Metagratings of type A comprise parallel rods of InSb on silicon-dioxide substrate, whereas the substrate is also made of InSb in metagratings of type B. Both types exhibit thermally controllable deflection and asymmetric transmission, which occur when the real part of the relative permittivity of InSb is high. Narrowband features in the sub-diffraction regime may appear in a wide frequency range which involves the vicinity of the vacuum state, the real part of the relative permittivity of InSb being low then.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The planewave-response characteristics of simple lamellar metagratings exhibiting thermally mediated transmission-mode deflection (blazing) were numerically investigated, the unit cell of each metagrating containing a phase-change material chosen to be indium antimonide (InSb). Thermal control arises from the use of InSb in its insulator phase and the vicinity of the vacuum state. Metagratings of type A comprise parallel rods of InSb on silicon-dioxide substrate, whereas the substrate is also made of InSb in metagratings of type B. Both types exhibit thermally controllable deflection and asymmetric transmission, which occur when the real part of the relative permittivity of InSb is high. Narrowband features in the sub-diffraction regime may appear in a wide frequency range which involves the vicinity of the vacuum state, the real part of the relative permittivity of InSb being low then.
334.
Andriy E Serebryannikov, E Ozbay
Exploring localized ENZ resonances and their role in superscattering, wideband invisibility, and tunable scattering Journal Article
In: Scientific Reports, vol. 14, no. 1, pp. 1580, 2024.
@article{Serebryannikov2024,
title = {Exploring localized ENZ resonances and their role in superscattering, wideband invisibility, and tunable scattering},
author = {Andriy E Serebryannikov and E Ozbay},
doi = {10.1038/s41598-024-51503-y},
year = {2024},
date = {2024-01-18},
urldate = {2024-01-18},
journal = {Scientific Reports},
volume = {14},
number = {1},
pages = {1580},
abstract = {While the role and manifestations of the localized surface plasmon resonances (LSPRs) in anomalous scattering, like superscattering and invisibility, are quite well explored, the existence, appearance, and possible contribution of localized epsilon-near-zero (ENZ) resonances still invoke careful exploration. In this paper, that is done along with a comparison of the resonances of two types in the case of thin-wall cylinders made of lossy and loss-compensated dispersive materials. It is shown that the localized ENZ resonances exist and appear very close to the zero-permittivity regime, i.e., at near-zero but yet negative permittivity that is similar to the ENZ modes in thin planar films. Near- and far-field characteristics of the superscattering modes are investigated. The results indicate that the scattering regimes arising due to LSPRs and localized ENZ resonances are distinguishable in terms of the basic field features inside and around the scatterer and differ in their contribution to the resulting scattering mechanism, e.g., in terms of the occupied frequency and permittivity ranges as well as the sensitivity to the wall thickness variations. When the losses are either weak or tend to zero due to the doping with gain enabling impurities, the sharp peaks of the scattering cross-section that are yielded by the resonances can be said to be embedded into the otherwise wide invisibility range. In the case of lossy material, a wide and continuous invisibility range is shown to appear not only due to a small total volume of the scatterer in the nonresonant regime, but also because high-Q superscattering modes are suppressed by the losses. For numerical demonstration, indium antimonide, a natural lossy material, and a hypothetical, properly doped material with the same real part of the permittivity but lower or zero losses are considered. In the latter case, variations of permittivity with a control parameter can be adjusted in such a way that transitions from one superscattering mode to another can be achieved. In turn, transition from the strong-scattering to the invisibility regime is possible even for the original lossy material. The basic properties of the studied superscattering modes may be replicable in artificial structures comprising natural low-loss materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
While the role and manifestations of the localized surface plasmon resonances (LSPRs) in anomalous scattering, like superscattering and invisibility, are quite well explored, the existence, appearance, and possible contribution of localized epsilon-near-zero (ENZ) resonances still invoke careful exploration. In this paper, that is done along with a comparison of the resonances of two types in the case of thin-wall cylinders made of lossy and loss-compensated dispersive materials. It is shown that the localized ENZ resonances exist and appear very close to the zero-permittivity regime, i.e., at near-zero but yet negative permittivity that is similar to the ENZ modes in thin planar films. Near- and far-field characteristics of the superscattering modes are investigated. The results indicate that the scattering regimes arising due to LSPRs and localized ENZ resonances are distinguishable in terms of the basic field features inside and around the scatterer and differ in their contribution to the resulting scattering mechanism, e.g., in terms of the occupied frequency and permittivity ranges as well as the sensitivity to the wall thickness variations. When the losses are either weak or tend to zero due to the doping with gain enabling impurities, the sharp peaks of the scattering cross-section that are yielded by the resonances can be said to be embedded into the otherwise wide invisibility range. In the case of lossy material, a wide and continuous invisibility range is shown to appear not only due to a small total volume of the scatterer in the nonresonant regime, but also because high-Q superscattering modes are suppressed by the losses. For numerical demonstration, indium antimonide, a natural lossy material, and a hypothetical, properly doped material with the same real part of the permittivity but lower or zero losses are considered. In the latter case, variations of permittivity with a control parameter can be adjusted in such a way that transitions from one superscattering mode to another can be achieved. In turn, transition from the strong-scattering to the invisibility regime is possible even for the original lossy material. The basic properties of the studied superscattering modes may be replicable in artificial structures comprising natural low-loss materials.
333.
A O Cakmak, E Colak, Andriy E Serebryannikov
Using Thin Films of Phase-Change Material for Active Tuning of Terahertz Waves Scattering on Dielectric Cylinders Journal Article
In: Materials, vol. 17, no. 1, 2024, ISBN: 1996-1944.
@article{ma17010260,
title = {Using Thin Films of Phase-Change Material for Active Tuning of Terahertz Waves Scattering on Dielectric Cylinders},
author = {A O Cakmak and E Colak and Andriy E Serebryannikov},
url = {https://www.mdpi.com/1996-1944/17/1/260},
doi = {10.3390/ma17010260},
isbn = {1996-1944},
year = {2024},
date = {2024-01-04},
journal = {Materials},
volume = {17},
number = {1},
abstract = {The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide (VO2) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO2, a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase. The shells that uniformly cover the dielectric cylinders are investigated. Attention will be paid to the demonstration of the potential of VO2 in the external control of diverse scattering regimes of the dielectric-VO2 core-shell scatterer, while conductivity of VO2 corresponds to rather insignificant variations in temperature. In line with the purposes of this work, it is shown that the different resonant and nonresonant regimes have different sensitivity to the variations in VO2 conductivity. Both the total scattering cross section and field distributions inside and around the core are studied, as well as the angle-dependent scattering cross section.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The scattering of electromagnetic waves by isotropic dielectric cylinders can be dramatically modified by means of vanadium dioxide (VO2) thin-film coatings. Efficient dynamic control of scattering is achieved due to the variations in material parameters realizable by means of external biasing. In this paper, we study the scattering of terahertz waves in a case where the coating shells are made of VO2, a phase-change material, whose thin films may work rather as electromagnetic phase screens in the insulator material phase, but as lossy quasi-metallic components in the metallic material phase. The shells that uniformly cover the dielectric cylinders are investigated. Attention will be paid to the demonstration of the potential of VO2 in the external control of diverse scattering regimes of the dielectric-VO2 core–shell scatterer, while conductivity of VO2 corresponds to rather insignificant variations in temperature. In line with the purposes of this work, it is shown that the different resonant and nonresonant regimes have different sensitivity to the variations in VO2 conductivity. Both the total scattering cross section and field distributions inside and around the core are studied, as well as the angle-dependent scattering cross section.
332.
Sreedevi Janardhanan, Sławomir Mielcarek, H Głowiński, D Kiphart, P Kuświk, Aleksandra Trzaskowska
Spin wave dynamics in CoFeB bilayers with wedged Au spacer Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 589, pp. 171570, 2024.
@article{JANARDHANAN2024171570,
title = {Spin wave dynamics in CoFeB bilayers with wedged Au spacer},
author = {Sreedevi Janardhanan and Sławomir Mielcarek and H Głowiński and D Kiphart and P Kuświk and Aleksandra Trzaskowska},
doi = {https://doi.org/10.1016/j.jmmm.2023.171570},
year = {2024},
date = {2024-01-01},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {589},
pages = {171570},
abstract = {This paper presents the experimental studies of ferromagnetic layers separated by a heavy metal wedge. The studied system consists of two thin layers of CoFeB separated by a wedged Au spacer. By performing Brillouin light scattering measurements of the spin-wave dispersion relations, and dependences on the magnetic field, we extract magnetic parameters in the studied ferromagnetic layers as a function of heavy metal thickness. We concluded that for thin ferromagnetic double layers, the magnetic properties strongly depend on the thickness of the wedge gold layer spacer. In particular, the presence of perpendicular magnetic anisotropy diminishes as the thickness of the magnetic material is increased, and at the spacers thicker than 2.5 nm the dynamic coupling between propagating spin waves in both layers is negligible. These findings have potential advantages for the development of future spintronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper presents the experimental studies of ferromagnetic layers separated by a heavy metal wedge. The studied system consists of two thin layers of CoFeB separated by a wedged Au spacer. By performing Brillouin light scattering measurements of the spin-wave dispersion relations, and dependences on the magnetic field, we extract magnetic parameters in the studied ferromagnetic layers as a function of heavy metal thickness. We concluded that for thin ferromagnetic double layers, the magnetic properties strongly depend on the thickness of the wedge gold layer spacer. In particular, the presence of perpendicular magnetic anisotropy diminishes as the thickness of the magnetic material is increased, and at the spacers thicker than 2.5 nm the dynamic coupling between propagating spin waves in both layers is negligible. These findings have potential advantages for the development of future spintronic devices.
2023
331.
P V Bondarenko, Julia Kharlan, S A Bunyaev, O Salyuk, I R Aseguinolaza, J M Barandiaran, G N Kakazei, V Chernenko, V O Golub
Giant four-fold magnetic anisotropy in nanotwinned NiMnGa epitaxial films Journal Article
In: APL Materials, vol. 11, no. 12, pp. 121114, 2023.
@article{10.1063/5.0162561,
title = {Giant four-fold magnetic anisotropy in nanotwinned NiMnGa epitaxial films},
author = {P V Bondarenko and Julia Kharlan and S A Bunyaev and O Salyuk and I R Aseguinolaza and J M Barandiaran and G N Kakazei and V Chernenko and V O Golub},
doi = {10.1063/5.0162561},
year = {2023},
date = {2023-12-22},
urldate = {2023-12-22},
journal = {APL Materials},
volume = {11},
number = {12},
pages = {121114},
abstract = {A giant four-fold magnetic anisotropy (with an anisotropy field up to 4 kOe) was observed in the twinned NiMnGa epitaxial film. Its appearance is explained in terms of moderate coupling between twin variants having strong uniaxial magnetocrystalline anisotropies directed orthogonally when the intertwin exchange field is comparable with the anisotropy field. This finding paves the way to increase the order of magnetic anisotropy in a many-component system while keeping the value of the anisotropy field by tuning the intercomponent exchange strength and can be extended to exchange-coupled multilayers and arrays of nanoelements.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A giant four-fold magnetic anisotropy (with an anisotropy field up to 4 kOe) was observed in the twinned NiMnGa epitaxial film. Its appearance is explained in terms of moderate coupling between twin variants having strong uniaxial magnetocrystalline anisotropies directed orthogonally when the intertwin exchange field is comparable with the anisotropy field. This finding paves the way to increase the order of magnetic anisotropy in a many-component system while keeping the value of the anisotropy field by tuning the intercomponent exchange strength and can be extended to exchange-coupled multilayers and arrays of nanoelements.
330.
Sreedevi Janardhanan, Sławomir Mielcarek, H Głowiński, M Kowacz, Maciej Krawczyk, Aleksandra Trzaskowska
Investigation of spin wave dynamics in Au/CoFeB/Au multilayers with perpendicular magnetic anisotropy Journal Article
In: Scientific Report, vol. 13, pp. 22494 , 2023.
@article{janardhanan_scirep_2023,
title = {Investigation of spin wave dynamics in Au/CoFeB/Au multilayers with perpendicular magnetic anisotropy},
author = {Sreedevi Janardhanan and Sławomir Mielcarek and H Głowiński and M Kowacz and Maciej Krawczyk and Aleksandra Trzaskowska
},
year = {2023},
date = {2023-12-15},
journal = {Scientific Report},
volume = {13},
pages = {22494 },
abstract = {We have carried out an experimental investigation of the spin-wave dynamics in the Au/CoFeB/Au multilayer consisting of a ferromagnetic film with thicknesses of 0.8, 0.9 and 1.0 nm. We employed the Brillouin light scattering spectroscopy to measure the frequency of the spin waves in dependence on the wave vector. Additionally, we characterized the samples by ferromagnetic resonance measurements. We found that the considered samples exhibit perpendicular magnetic anisotropy with low damping, indicating small pumping effects. Furthermore, we found a nonreciprocal dispersion relation pointing at a non-negligible Dzyaloshinskii–Moriya interaction. These results make the Au/CoFeB/Au multilayer a compelling subject for further analysis and as a potential material for future applications within magnonics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have carried out an experimental investigation of the spin-wave dynamics in the Au/CoFeB/Au multilayer consisting of a ferromagnetic film with thicknesses of 0.8, 0.9 and 1.0 nm. We employed the Brillouin light scattering spectroscopy to measure the frequency of the spin waves in dependence on the wave vector. Additionally, we characterized the samples by ferromagnetic resonance measurements. We found that the considered samples exhibit perpendicular magnetic anisotropy with low damping, indicating small pumping effects. Furthermore, we found a nonreciprocal dispersion relation pointing at a non-negligible Dzyaloshinskii–Moriya interaction. These results make the Au/CoFeB/Au multilayer a compelling subject for further analysis and as a potential material for future applications within magnonics.
329.
Krzysztof Szulc, K Pydzińska-Białek, M Ziółek
Modeling of Charge Injection, Recombination, and Diffusion in Complete Perovskite Solar Cells on Short Time Scales Journal Article
In: Materials, vol. 16, no. 22, pp. 7110, 2023, ISBN: 1996-1944.
@article{ma16227110,
title = {Modeling of Charge Injection, Recombination, and Diffusion in Complete Perovskite Solar Cells on Short Time Scales},
author = {Krzysztof Szulc and K Pydzińska-Białek and M Ziółek},
url = {https://www.mdpi.com/1996-1944/16/22/7110},
doi = {10.3390/ma16227110},
isbn = {1996-1944},
year = {2023},
date = {2023-11-10},
journal = {Materials},
volume = {16},
number = {22},
pages = {7110},
abstract = {A model of charge population decay upon ultrafast optical pulse excitation in complete, working perovskite solar cells is proposed. The equation, including charge injections (extractions) from perovskite to contact materials, charge diffusion, and charge recombination via first-, second-, and third-order processes, is solved using numerical simulations. Results of simulations are positively verified by broadband transient absorption results of mixed halide, triple-cation perovskite (FA0.76MA0.19Cs0.05Pb(I0.81Br0.19)3). The combined analytical and experimental findings reveal the best approaches for the proper determination of the crucial parameters that govern charge transfer dynamics in perovskite solar cells on picosecond and single nanosecond time scales. Measurements from both electron and hole transporting layer sides under different applied bias potentials (zero and close to open circuit potential) and different pump fluence (especially below 5 μJ/cm2), followed by fitting of parameters using numerical modeling, are proposed as the optimal methodology for describing the processes taking place in efficient devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A model of charge population decay upon ultrafast optical pulse excitation in complete, working perovskite solar cells is proposed. The equation, including charge injections (extractions) from perovskite to contact materials, charge diffusion, and charge recombination via first-, second-, and third-order processes, is solved using numerical simulations. Results of simulations are positively verified by broadband transient absorption results of mixed halide, triple-cation perovskite (FA0.76MA0.19Cs0.05Pb(I0.81Br0.19)3). The combined analytical and experimental findings reveal the best approaches for the proper determination of the crucial parameters that govern charge transfer dynamics in perovskite solar cells on picosecond and single nanosecond time scales. Measurements from both electron and hole transporting layer sides under different applied bias potentials (zero and close to open circuit potential) and different pump fluence (especially below 5 μJ/cm2), followed by fitting of parameters using numerical modeling, are proposed as the optimal methodology for describing the processes taking place in efficient devices.
328.
X Liang, J Lan, G Zhao, Mateusz Zelent, Maciej Krawczyk, Y Zhou
Bidirectional magnon-driven bimeron motion in ferromagnets Journal Article
In: Phys. Rev. B, vol. 108, iss. 18, no. 8, pp. 184407, 2023.
@article{PhysRevB.108.184407,
title = {Bidirectional magnon-driven bimeron motion in ferromagnets},
author = {X Liang and J Lan and G Zhao and Mateusz Zelent and Maciej Krawczyk and Y Zhou},
url = {https://link.aps.org/doi/10.1103/PhysRevB.108.184407},
doi = {10.1103/PhysRevB.108.184407},
year = {2023},
date = {2023-11-08},
journal = {Phys. Rev. B},
volume = {108},
number = {8},
issue = {18},
pages = {184407},
abstract = {As the in-plane magnetized counterparts of skyrmions in two dimensions, magnetic bimerons are swirling topological spin textures consisting of two merons. Here we theoretically and numerically investigate the dynamics of a bimeron induced by the monochromatic spin wave in a ferromagnetic thin film. The micromagnetic simulation results reveal that unlike the ferromagnetic skyrmion reported in previous studies, the bimeron can be pushed away from (or pulled towards) the wave source at the low (high) spin wave frequency. These numerical results are in line with the particle collision model formulating the interplay between the spin wave and magnetic bimeron. Our findings provide guidelines for constructing future bimeron-based spintronic devices with ultralow energy consumption.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
As the in-plane magnetized counterparts of skyrmions in two dimensions, magnetic bimerons are swirling topological spin textures consisting of two merons. Here we theoretically and numerically investigate the dynamics of a bimeron induced by the monochromatic spin wave in a ferromagnetic thin film. The micromagnetic simulation results reveal that unlike the ferromagnetic skyrmion reported in previous studies, the bimeron can be pushed away from (or pulled towards) the wave source at the low (high) spin wave frequency. These numerical results are in line with the particle collision model formulating the interplay between the spin wave and magnetic bimeron. Our findings provide guidelines for constructing future bimeron-based spintronic devices with ultralow energy consumption.
327.
Sławomir Mamica
The influence of the demagnetizing field on the concentration of spin wave energy in two-dimensional magnonic crystals Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 588, pp. 171395, 2023.
@article{MAMICA2023171395,
title = {The influence of the demagnetizing field on the concentration of spin wave energy in two-dimensional magnonic crystals},
author = {Sławomir Mamica},
year = {2023},
date = {2023-10-21},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {588},
pages = {171395},
abstract = {We use the Plane Wave Method to theoretically study thin-film magnonic crystals (MCs) composed of two very common magnetic materials: cobalt and permalloy. In both cases, we consider Co inclusions in the Py matrix and Py inclusions in the Co matrix. An external magnetic field is applied in the plane of the structure, leading to the formation of a demagnetizing field at the interface between the inclusions and matrix. Previous studies have shown that this field strongly affects the spectrum of spin waves, including the position and width of bandgaps. In this study, we exploit the in-plane squeezing of the MC structure to enhance the demagnetizing field. This results in the transfer of low-frequency spin waves from Py to Co, affecting the energy distribution (i.e., the spin-wave profile). The change in the concentration of spin-wave profiles leads to certain peculiarities in the spin-wave frequency spectrum. These include modes repulsion caused by hybridization, which in turn leads to the reordering of modes in the spectrum.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We use the Plane Wave Method to theoretically study thin-film magnonic crystals (MCs) composed of two very common magnetic materials: cobalt and permalloy. In both cases, we consider Co inclusions in the Py matrix and Py inclusions in the Co matrix. An external magnetic field is applied in the plane of the structure, leading to the formation of a demagnetizing field at the interface between the inclusions and matrix. Previous studies have shown that this field strongly affects the spectrum of spin waves, including the position and width of bandgaps. In this study, we exploit the in-plane squeezing of the MC structure to enhance the demagnetizing field. This results in the transfer of low-frequency spin waves from Py to Co, affecting the energy distribution (i.e., the spin-wave profile). The change in the concentration of spin-wave profiles leads to certain peculiarities in the spin-wave frequency spectrum. These include modes repulsion caused by hybridization, which in turn leads to the reordering of modes in the spectrum.
326.
A.K. Dhiman, R. Gieniusz, J. Kisielewski, P. Mazalski, M. Matczak, F. Stobiecki, Paweł Gruszecki, Maciej Krawczyk, A. Lynnyk, A. Maziewski
Hysteresis of magnetization statics and dynamics in [Pt/Co] multilayer Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 587, no. 171338, 2023, ISBN: 0304-8853.
@article{DHIMAN2023171338,
title = {Hysteresis of magnetization statics and dynamics in [Pt/Co] multilayer},
author = {A.K. Dhiman and R. Gieniusz and J. Kisielewski and P. Mazalski and M. Matczak and F. Stobiecki and Paweł Gruszecki and Maciej Krawczyk and A. Lynnyk and A. Maziewski},
url = {https://www.sciencedirect.com/science/article/pii/S0304885323009885},
doi = {https://doi.org/10.1016/j.jmmm.2023.171338},
isbn = {0304-8853},
year = {2023},
date = {2023-10-11},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {587},
number = {171338},
abstract = {The magnetic multilayer of Co separated by thin spacer layer of Pt was deposited by DC-magnetron sputtering. From the longitudinal magneto-optical Kerr effect based magnetometry and microscopy as well as magnetic force microscopy, the hybrid magnetization structure was deduced: the large size, micrometer scale magnetic domains with in-plane “core magnetization” patterned by nanometer scale domains with out-of-plane components. The hysteresis as a function of in-plane applied magnetic field of both: (i) magnetization curve measured by Superconducting Quantum Interference Device and (ii) dynamic responses measured by broadband Vector Network Analyzer spectroscopy were observed. The experimental results are well described by micromagnetic simulations. These magnetic history dependent effects were explained by magnetization cores, with in plane component, switching.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The magnetic multilayer of Co separated by thin spacer layer of Pt was deposited by DC-magnetron sputtering. From the longitudinal magneto-optical Kerr effect based magnetometry and microscopy as well as magnetic force microscopy, the hybrid magnetization structure was deduced: the large size, micrometer scale magnetic domains with in-plane “core magnetization” patterned by nanometer scale domains with out-of-plane components. The hysteresis as a function of in-plane applied magnetic field of both: (i) magnetization curve measured by Superconducting Quantum Interference Device and (ii) dynamic responses measured by broadband Vector Network Analyzer spectroscopy were observed. The experimental results are well described by micromagnetic simulations. These magnetic history dependent effects were explained by magnetization cores, with in plane component, switching.
325.
Gauthier Philippe, Mathieu Moalic, Jarosław W Kłos
Unidirectional spin wave emission by traveling pair of magnetic field profiles Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 587, pp. 171359, 2023.
@article{PHILIPPE2023171359,
title = {Unidirectional spin wave emission by traveling pair of magnetic field profiles},
author = {Gauthier Philippe and Mathieu Moalic and Jarosław W Kłos},
doi = {https://doi.org/10.1016/j.jmmm.2023.171359},
year = {2023},
date = {2023-10-04},
urldate = {2023-10-04},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {587},
pages = {171359},
abstract = {We demonstrate that the spin wave Cherenkov effect can be used to design the unidirectional spin wave emitter with tunable frequency and switchable direction of emission. In our numerical studies, we propose to use a pair of traveling profiles of the magnetic field which generate the spin waves, for sufficiently large velocity of their motion. In the considered system, the spin waves of shorter (longer) wavelengths are induced at the front (back) of the moving profiles and interfere constructively or destructively, depending on the velocity of the profiles. Moreover, we showed that the spin waves can be confined between the pair of traveling profiles of the magnetic field. This work opens the perspectives for the experimental studies in hybrid magnonic-superconducting systems where the magnetic vortices in a superconductor can be used as moving sources of the magnetic field driving the spin waves in the ferromagnetic subsystem.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We demonstrate that the spin wave Cherenkov effect can be used to design the unidirectional spin wave emitter with tunable frequency and switchable direction of emission. In our numerical studies, we propose to use a pair of traveling profiles of the magnetic field which generate the spin waves, for sufficiently large velocity of their motion. In the considered system, the spin waves of shorter (longer) wavelengths are induced at the front (back) of the moving profiles and interfere constructively or destructively, depending on the velocity of the profiles. Moreover, we showed that the spin waves can be confined between the pair of traveling profiles of the magnetic field. This work opens the perspectives for the experimental studies in hybrid magnonic-superconducting systems where the magnetic vortices in a superconductor can be used as moving sources of the magnetic field driving the spin waves in the ferromagnetic subsystem.
324.
Grzegorz Centała, Jarosław W Kłos
Shaping magnetization dynamics in a planar square dot by adjusting its surface anisotropy Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 587, pp. 171254, 2023.
@article{CENTALA2023171254,
title = {Shaping magnetization dynamics in a planar square dot by adjusting its surface anisotropy},
author = {Grzegorz Centała and Jarosław W Kłos},
url = {https://www.sciencedirect.com/science/article/pii/S0304885323009046},
doi = {https://doi.org/10.1016/j.jmmm.2023.171254},
year = {2023},
date = {2023-09-22},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {587},
pages = {171254},
abstract = {A planar square dot is one of the simplest structures confined to three dimensions. Despite its geometrical simplicity, the description of the spin wave modes in this structure is not trivial due to the competition of dipolar and exchange interactions. An additional factor that makes this description challenging are the boundary conditions depend both on non-local dipolar interactions and local surface parameters such as surface anisotropy. In the presented work, we showed how the surface anisotropy applied at the lateral faces of the dot can tune the frequency of fundamental mode in the planar CoFeB dot, magnetized in an out-of-plane direction. Moreover, we analyzed the spin wave profile of the fundamental mode and the corresponding dynamic stray field. We showed that the asymmetric application of surface anisotropy produces an asymmetric profile of dynamic stray field for square dot and can be used to tailor inter-dot coupling. The calculations were performed with the use of the finite-element method.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A planar square dot is one of the simplest structures confined to three dimensions. Despite its geometrical simplicity, the description of the spin wave modes in this structure is not trivial due to the competition of dipolar and exchange interactions. An additional factor that makes this description challenging are the boundary conditions depend both on non-local dipolar interactions and local surface parameters such as surface anisotropy. In the presented work, we showed how the surface anisotropy applied at the lateral faces of the dot can tune the frequency of fundamental mode in the planar CoFeB dot, magnetized in an out-of-plane direction. Moreover, we analyzed the spin wave profile of the fundamental mode and the corresponding dynamic stray field. We showed that the asymmetric application of surface anisotropy produces an asymmetric profile of dynamic stray field for square dot and can be used to tailor inter-dot coupling. The calculations were performed with the use of the finite-element method.
323.
Sreedevi Janardhanan, Sławomir Mielcarek, P Kuświk, Maciej Krawczyk, Aleksandra Trzaskowska
High-resolution Brillouin light scattering study on Ti/Au/Co/Ni multilayer Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 586, pp. 171209, 2023.
@article{JANARDHANAN2023171209,
title = {High-resolution Brillouin light scattering study on Ti/Au/Co/Ni multilayer},
author = {Sreedevi Janardhanan and Sławomir Mielcarek and P Kuświk and Maciej Krawczyk and Aleksandra Trzaskowska},
url = {https://www.sciencedirect.com/science/article/pii/S0304885323008594},
doi = {https://doi.org/10.1016/j.jmmm.2023.171209},
year = {2023},
date = {2023-09-04},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {586},
pages = {171209},
abstract = {The topic of this paper addresses the Brillouin light scattering (BLS) study of the spin-wave and surface acoustic wave dynamics in the multilayer consisting of Ti/Au/Co/Ni deposited on Si substrate. We make the quantitative analysis of spin-wave frequency under a range of wave vectors to determine the dispersion relation and to study the effect of the magnetic field. These findings were correlated with theoretical models to determine the magnetic system parameters, such as magnetization, Lande g factor, exchange stiffness constant etc. In addition to this, we have conducted finite element method based simulations to understand the nature of surface phonons and to determine the elastic tensor parameters for the Ti/Au/Co/Ni layer from the fitting of simulation results with the experiment data points.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The topic of this paper addresses the Brillouin light scattering (BLS) study of the spin-wave and surface acoustic wave dynamics in the multilayer consisting of Ti/Au/Co/Ni deposited on Si substrate. We make the quantitative analysis of spin-wave frequency under a range of wave vectors to determine the dispersion relation and to study the effect of the magnetic field. These findings were correlated with theoretical models to determine the magnetic system parameters, such as magnetization, Lande g factor, exchange stiffness constant etc. In addition to this, we have conducted finite element method based simulations to understand the nature of surface phonons and to determine the elastic tensor parameters for the Ti/Au/Co/Ni layer from the fitting of simulation results with the experiment data points.
322.
Mateusz Zelent, Mathieu Moalic, Michał Mruczkiewicz, X Li, Y Zhou, Maciej Krawczyk
Stabilization and racetrack application of asymmetric Néel skyrmions in hybrid nanostructures Journal Article
In: Scientific Reports, vol. 13, iss. 1, pp. 13572, 2023.
@article{zelent_stabilization2023,
title = {Stabilization and racetrack application of asymmetric Néel skyrmions in hybrid nanostructures},
author = {Mateusz Zelent and Mathieu Moalic and Michał Mruczkiewicz and X Li and Y Zhou and Maciej Krawczyk},
doi = {10.1038/s41598-023-40236-z},
year = {2023},
date = {2023-08-21},
journal = {Scientific Reports},
volume = {13},
issue = {1},
pages = {13572},
abstract = {Magnetic skyrmions, topological quasiparticles, are small stable magnetic textures that possess intriguing properties and potential for data storage applications. Hybrid nanostructures comprised of skyrmions and soft magnetic material can offer additional advantages for developing skyrmion-based spintronic and magnonic devices. We show that a Néel-type skyrmion confined within a nanodot placed on top of a ferromagnetic in-plane magnetized stripe produces a unique and compelling platform for exploring the mutual coupling between magnetization textures. The skyrmion induces an imprint upon the stripe, which, in turn, asymmetrically squeezes the skyrmion in the dot, increasing their size and the range of skyrmion stability at small values of Dzyaloshinskii–Moriya interaction, as well as introducing skyrmion bi-stability. Finally, by exploiting the properties of the skyrmion in a hybrid system, we demonstrate unlimited skyrmion transport along a racetrack, free of the skyrmion Hall effect.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Magnetic skyrmions, topological quasiparticles, are small stable magnetic textures that possess intriguing properties and potential for data storage applications. Hybrid nanostructures comprised of skyrmions and soft magnetic material can offer additional advantages for developing skyrmion-based spintronic and magnonic devices. We show that a Néel-type skyrmion confined within a nanodot placed on top of a ferromagnetic in-plane magnetized stripe produces a unique and compelling platform for exploring the mutual coupling between magnetization textures. The skyrmion induces an imprint upon the stripe, which, in turn, asymmetrically squeezes the skyrmion in the dot, increasing their size and the range of skyrmion stability at small values of Dzyaloshinskii–Moriya interaction, as well as introducing skyrmion bi-stability. Finally, by exploiting the properties of the skyrmion in a hybrid system, we demonstrate unlimited skyrmion transport along a racetrack, free of the skyrmion Hall effect.
321.
V L'vov, Julia Kharlan, V Golub
Nonrelaxational FMR peak broadening in spatially inhomogeneous films Journal Article
In: Journal of Magnetism and Magnetic Materials, vol. 580, pp. 170906, 2023.
@article{LVOV2023170906,
title = {Nonrelaxational FMR peak broadening in spatially inhomogeneous films},
author = {V L'vov and Julia Kharlan and V Golub},
doi = {https://doi.org/10.1016/j.jmmm.2023.170906},
year = {2023},
date = {2023-08-15},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {580},
pages = {170906},
abstract = {The modification of magnetic properties in spatially inhomogeneous epitaxial films of magnetic shape memory alloys in martensitic state with the temperature variation has been studied. The proposed theoretical model is based on Landau theory of martensitic transformation and statistical model of martensitic state. It was shown that that spatial inhomogeneity of the material leads to the dispersion of local martensitic transformation temperatures resulting in the variation of local magnetic anisotropy values. This model allows describing the dramatic ferromagnetic resonance line broadening observed in the experiments in epitaxial films of magnetic shape memory alloys at low temperatures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The modification of magnetic properties in spatially inhomogeneous epitaxial films of magnetic shape memory alloys in martensitic state with the temperature variation has been studied. The proposed theoretical model is based on Landau theory of martensitic transformation and statistical model of martensitic state. It was shown that that spatial inhomogeneity of the material leads to the dispersion of local martensitic transformation temperatures resulting in the variation of local magnetic anisotropy values. This model allows describing the dramatic ferromagnetic resonance line broadening observed in the experiments in epitaxial films of magnetic shape memory alloys at low temperatures.
320.
Grzegorz Centała, Jarosław W Kłos
Compact localized states in magnonic Lieb lattices Journal Article
In: Scientific Reports, vol. 13, iss. 1, pp. 12676, 2023.
@article{centala2023,
title = {Compact localized states in magnonic Lieb lattices},
author = {Grzegorz Centała and Jarosław W Kłos},
url = {https://doi.org/10.1038/s41598-023-39816-w},
year = {2023},
date = {2023-08-04},
journal = {Scientific Reports},
volume = {13},
issue = {1},
pages = {12676},
abstract = {Lieb lattice is one of the simplest bipartite lattices, where compact localized states (CLS) are observed. This type of localization is induced by the peculiar topology of the unit cell, where the modes are localized only on selected sublattices due to the destructive interference of partial waves. We demonstrate the possibility of magnonic Lieb lattice realization, where flat bands and CLS can be observed in the planar structure of sub-micron in-plane sizes. Using forward volume configuration, the Ga-doped YIG layer with cylindrical inclusions (without Ga content) arranged in a Lieb lattice with 250 nm period was investigated numerically (finite-element method). The structure was tailored to observe, for a lowest magnonic bands, the oscillatory and evanescent spin waves in inclusions and matrix, respectively. Such a design reproduces the Lieb lattice of nodes (inclusions) coupled to each other by the matrix with the CLS in flat bands.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lieb lattice is one of the simplest bipartite lattices, where compact localized states (CLS) are observed. This type of localization is induced by the peculiar topology of the unit cell, where the modes are localized only on selected sublattices due to the destructive interference of partial waves. We demonstrate the possibility of magnonic Lieb lattice realization, where flat bands and CLS can be observed in the planar structure of sub-micron in-plane sizes. Using forward volume configuration, the Ga-doped YIG layer with cylindrical inclusions (without Ga content) arranged in a Lieb lattice with 250 nm period was investigated numerically (finite-element method). The structure was tailored to observe, for a lowest magnonic bands, the oscillatory and evanescent spin waves in inclusions and matrix, respectively. Such a design reproduces the Lieb lattice of nodes (inclusions) coupled to each other by the matrix with the CLS in flat bands.
319.
Krzysztof Sobucki, Wojciech Śmigaj, Piotr Graczyk, Maciej Krawczyk, Paweł Gruszecki
Magnon-Optic Effects with Spin-Wave Leaky Modes: Tunable Goos-Hänchen Shift and Wood’s Anomaly Journal Article
In: Nano Letters, vol. 23, iss. 15, no. 6979–6984, 2023.
@article{sobucki2023b,
title = {Magnon-Optic Effects with Spin-Wave Leaky Modes: Tunable Goos-Hänchen Shift and Wood’s Anomaly},
author = {Krzysztof Sobucki and Wojciech Śmigaj and Piotr Graczyk and Maciej Krawczyk and Paweł Gruszecki},
url = {https://doi.org/10.1021/acs.nanolett.3c01592},
doi = {10.1021/acs.nanolett.3c01592},
year = {2023},
date = {2023-07-31},
urldate = {2023-07-31},
journal = {Nano Letters},
volume = {23},
number = {6979–6984},
issue = {15},
abstract = {We demonstrate numerically how a spin wave (SW) beam obliquely incident on the edge of a thin film placed below a ferromagnetic stripe can excite leaky SWs guided along the stripe. During propagation, leaky waves emit energy back into the layer in the form of plane waves and several laterally shifted parallel SW beams. This resonance excitation, combined with interference effects of the reflected and re-emitted waves, results in the magnonic Wood’s anomaly and a significant increase of the Goos-Hänchen shift magnitude. This yields a unique platform to control SW reflection and transdimensional magnonic router that can transfer SWs from a 2D platform into a 1D guided mode.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We demonstrate numerically how a spin wave (SW) beam obliquely incident on the edge of a thin film placed below a ferromagnetic stripe can excite leaky SWs guided along the stripe. During propagation, leaky waves emit energy back into the layer in the form of plane waves and several laterally shifted parallel SW beams. This resonance excitation, combined with interference effects of the reflected and re-emitted waves, results in the magnonic Wood’s anomaly and a significant increase of the Goos-Hänchen shift magnitude. This yields a unique platform to control SW reflection and transdimensional magnonic router that can transfer SWs from a 2D platform into a 1D guided mode.
318.
Wojciech Śmigaj, Krzysztof Sobucki, Paweł Gruszecki, Maciej Krawczyk
Modal approach to modeling spin wave scattering Journal Article
In: Phys. Rev. B, vol. 108, iss. 1, no. 15, pp. 014418, 2023.
@article{PhysRevB.108.014418,
title = {Modal approach to modeling spin wave scattering},
author = {Wojciech Śmigaj and Krzysztof Sobucki and Paweł Gruszecki and Maciej Krawczyk},
url = {https://link.aps.org/doi/10.1103/PhysRevB.108.014418},
doi = {10.1103/PhysRevB.108.014418},
year = {2023},
date = {2023-07-14},
journal = {Phys. Rev. B},
volume = {108},
number = {15},
issue = {1},
pages = {014418},
abstract = {Efficient numerical methods are required for the design of optimized devices. In magnonics, the primary computational tool is micromagnetic simulations, which solve the Landau-Lifshitz equation discretized in time and space. However, their computational cost is high, and the complexity of their output hinders insight into the physics of the simulated system, especially in the case of multimode propagating-wave-based devices. We propose a finite-element modal method allowing an efficient solution of the scattering problem for dipole-exchange spin waves propagating perpendicularly to the magnetization direction. The method gives direct access to the scattering matrix of the whole system and its components. We extend the formula for the power carried by a magnetostatic mode in the Damon-Eshbach configuration to the case with exchange, allowing the scattering coefficients to be normalized to represent the fraction of the input power transferred to each output channel. We apply the method to the analysis of spin wave scattering on a basic functional block of magnonic circuits, consisting of a resonator dynamically coupled to a thin film. The results and the method are validated by comparison with micromagnetic simulations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Efficient numerical methods are required for the design of optimized devices. In magnonics, the primary computational tool is micromagnetic simulations, which solve the Landau-Lifshitz equation discretized in time and space. However, their computational cost is high, and the complexity of their output hinders insight into the physics of the simulated system, especially in the case of multimode propagating-wave-based devices. We propose a finite-element modal method allowing an efficient solution of the scattering problem for dipole-exchange spin waves propagating perpendicularly to the magnetization direction. The method gives direct access to the scattering matrix of the whole system and its components. We extend the formula for the power carried by a magnetostatic mode in the Damon-Eshbach configuration to the case with exchange, allowing the scattering coefficients to be normalized to represent the fraction of the input power transferred to each output channel. We apply the method to the analysis of spin wave scattering on a basic functional block of magnonic circuits, consisting of a resonator dynamically coupled to a thin film. The results and the method are validated by comparison with micromagnetic simulations.
317.
Shashank Shekhar, Sławomir Mielcarek, Y Otani, Bivas Rana, Aleksandra Trzaskowska
Influence of CoFeB layer thickness on elastic parameters in CoFeB/MgO heterostructures Journal Article
In: Scientific Reports , vol. 13, iss. 1, pp. 10668, 2023.
@article{Shekhar2023,
title = {Influence of CoFeB layer thickness on elastic parameters in CoFeB/MgO heterostructures},
author = {Shashank Shekhar and Sławomir Mielcarek and Y Otani and Bivas Rana and Aleksandra Trzaskowska},
doi = {10.1038/s41598-023-37808-4},
year = {2023},
date = {2023-07-01},
urldate = {2023-07-01},
journal = {Scientific Reports },
volume = {13},
issue = {1},
pages = {10668},
abstract = {The surface acoustic waves, i.e., surface phonons may have huge potential for future spintronic devices, if coupled to other waves (e.g., spin waves) or quasiparticles. In order to understand the coupling of acoustic phonons with the spin degree of freedom, especially in magnetic thin film-based heterostructures, one needs to investigate the properties of phonons in those heterostructures. This also allows us to determine the elastic properties of individual magnetic layers and the effective elastic parameters of the whole stacks. Here, we study frequency versus wavevector dispersion of thermally excited SAWs in CoFeB/MgO heterostructures with varying CoFeB thickness by employing Brillouin light spectroscopy. The experimental results are corroborated by finite element method-based simulations. From the best agreement of simulation results with the experiments, we find out the elastic tensor parameters for CoFeB layer. Additionally, we estimate the effective elastic parameters (elastic tensors, Young’s modulus, Poisson’s ratio) of the whole stacks for varying CoFeB thickness. Interestingly, the simulation results, either considering elastic parameters of individual layers or considering effective elastic parameters of whole stacks, show good agreement with the experimental results. These extracted elastic parameters will be very useful to understand the interaction of phonons with other quasiparticles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The surface acoustic waves, i.e., surface phonons may have huge potential for future spintronic devices, if coupled to other waves (e.g., spin waves) or quasiparticles. In order to understand the coupling of acoustic phonons with the spin degree of freedom, especially in magnetic thin film-based heterostructures, one needs to investigate the properties of phonons in those heterostructures. This also allows us to determine the elastic properties of individual magnetic layers and the effective elastic parameters of the whole stacks. Here, we study frequency versus wavevector dispersion of thermally excited SAWs in CoFeB/MgO heterostructures with varying CoFeB thickness by employing Brillouin light spectroscopy. The experimental results are corroborated by finite element method-based simulations. From the best agreement of simulation results with the experiments, we find out the elastic tensor parameters for CoFeB layer. Additionally, we estimate the effective elastic parameters (elastic tensors, Young’s modulus, Poisson’s ratio) of the whole stacks for varying CoFeB thickness. Interestingly, the simulation results, either considering elastic parameters of individual layers or considering effective elastic parameters of whole stacks, show good agreement with the experimental results. These extracted elastic parameters will be very useful to understand the interaction of phonons with other quasiparticles.
316.
Mateusz Gołębiewski, Hanna Reshetniak, Uladzislau Makartsou, Maciej Krawczyk, A van den Berg, S Ladak, A Barman
Spin-Wave Spectral Analysis in Crescent-Shaped Ferromagnetic Nanorods Journal Article
In: Phys. Rev. Appl., vol. 19, iss. 6, no. 10, pp. 064045, 2023.
@article{PhysRevApplied.19.064045,
title = {Spin-Wave Spectral Analysis in Crescent-Shaped Ferromagnetic Nanorods},
author = {Mateusz Gołębiewski and Hanna Reshetniak and Uladzislau Makartsou and Maciej Krawczyk and A van den Berg and S Ladak and A Barman},
url = {https://link.aps.org/doi/10.1103/PhysRevApplied.19.064045},
doi = {10.1103/PhysRevApplied.19.064045},
year = {2023},
date = {2023-06-14},
journal = {Phys. Rev. Appl.},
volume = {19},
number = {10},
issue = {6},
pages = {064045},
abstract = {The research on the properties of spin waves (SWs) in three-dimensional nanosystems is an innovative idea in the field of magnonics. Mastering and understanding the nature of magnetization dynamics and binding of SWs at surfaces, edges, and in-volume parts of three-dimensional magnetic systems enables the discovery of alternative phenomena and suggests other possibilities for their use in magnonic and spintronic devices. In this work, we use numerical methods to study the effect of geometry and external magnetic field manipulations on the localization and dynamics of SWs in crescent-shaped (CS) waveguides. It is shown that changing the magnetic field direction in these waveguides breaks the symmetry and affects the localization of eigenmodes with respect to the static demagnetizing field. This, in turn, has a direct effect on their frequency. Furthermore, CS structures are found to be characterized by significant saturation at certain field orientations, resulting in a cylindrical magnetization distribution. Thus, we present chirality-based nonreciprocal dispersion relations for high-frequency SWs, which can be controlled by the field direction (shape symmetry) and its amplitude (saturation).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The research on the properties of spin waves (SWs) in three-dimensional nanosystems is an innovative idea in the field of magnonics. Mastering and understanding the nature of magnetization dynamics and binding of SWs at surfaces, edges, and in-volume parts of three-dimensional magnetic systems enables the discovery of alternative phenomena and suggests other possibilities for their use in magnonic and spintronic devices. In this work, we use numerical methods to study the effect of geometry and external magnetic field manipulations on the localization and dynamics of SWs in crescent-shaped (CS) waveguides. It is shown that changing the magnetic field direction in these waveguides breaks the symmetry and affects the localization of eigenmodes with respect to the static demagnetizing field. This, in turn, has a direct effect on their frequency. Furthermore, CS structures are found to be characterized by significant saturation at certain field orientations, resulting in a cylindrical magnetization distribution. Thus, we present chirality-based nonreciprocal dispersion relations for high-frequency SWs, which can be controlled by the field direction (shape symmetry) and its amplitude (saturation).
315.
Bivas Rana, Y Otani
Anisotropy of magnetic damping in Ta/CoFeB/MgO heterostructures Journal Article
In: Scientific Reports, vol. 13, iss. 1, pp. 8532, 2023.
@article{Rana2023,
title = {Anisotropy of magnetic damping in Ta/CoFeB/MgO heterostructures},
author = {Bivas Rana and Y Otani},
doi = {10.1038/s41598-023-35739-8},
year = {2023},
date = {2023-05-26},
journal = {Scientific Reports},
volume = {13},
issue = {1},
pages = {8532},
abstract = {Magnetic damping controls the performance and operational speed of many spintronics devices. Being a tensor quantity, the damping in magnetic thin films often shows anisotropic behavior with the magnetization orientation. Here, we have studied the anisotropy of damping in Ta/CoFeB/MgO heterostructures, deposited on thermally oxidized Si substrates, as a function of the orientation of magnetization. By performing ferromagnetic resonance (FMR) measurements based on spin pumping and inverse spin Hall effect (ISHE), we extract the damping parameter in those films and find that the anisotropy of damping contains four-fold and two-fold anisotropy terms. We infer that four-fold anisotropy originates from two-magnon scattering (TMS). By studying reference Ta/CoFeB/MgO films, deposited on LiNbO3 substrates, we find that the two-fold anisotropy is correlated with in-plane magnetic anisotropy (IMA) of the films, suggesting its origin as the anisotropy in bulk spin–orbit coupling (SOC) of CoFeB film. We conclude that when IMA is very small, it’s correlation with two-fold anisotropy cannot be experimentally identified. However, as IMA increases, it starts to show a correlation with two-fold anisotropy in damping. These results will be beneficial for designing future spintronics devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Magnetic damping controls the performance and operational speed of many spintronics devices. Being a tensor quantity, the damping in magnetic thin films often shows anisotropic behavior with the magnetization orientation. Here, we have studied the anisotropy of damping in Ta/CoFeB/MgO heterostructures, deposited on thermally oxidized Si substrates, as a function of the orientation of magnetization. By performing ferromagnetic resonance (FMR) measurements based on spin pumping and inverse spin Hall effect (ISHE), we extract the damping parameter in those films and find that the anisotropy of damping contains four-fold and two-fold anisotropy terms. We infer that four-fold anisotropy originates from two-magnon scattering (TMS). By studying reference Ta/CoFeB/MgO films, deposited on LiNbO3 substrates, we find that the two-fold anisotropy is correlated with in-plane magnetic anisotropy (IMA) of the films, suggesting its origin as the anisotropy in bulk spin–orbit coupling (SOC) of CoFeB film. We conclude that when IMA is very small, it’s correlation with two-fold anisotropy cannot be experimentally identified. However, as IMA increases, it starts to show a correlation with two-fold anisotropy in damping. These results will be beneficial for designing future spintronics devices.
314.
Dariia Popadiuk, Elena Tartakovskaya, Maciej Krawczyk, K Y Guslienko
Emergent Magnetic Field and Nonzero Gyrovector of the Toroidal Magnetic Hopfion Journal Article
In: Rapid Research Letters, 2023.
@article{popadiuk2023,
title = {Emergent Magnetic Field and Nonzero Gyrovector of the Toroidal Magnetic Hopfion},
author = {Dariia Popadiuk and Elena Tartakovskaya and Maciej Krawczyk and K Y Guslienko},
url = {https://doi.org/10.1002/pssr.202300131},
year = {2023},
date = {2023-05-13},
journal = {Rapid Research Letters},
abstract = {Magnetic hopfions are localized magnetic solitons with a nonzero 3D topological
charge (Hopf index). Herein, an analytical calculation of the magnetic hopfion
gyrovector is presented and it is shown that it does not vanish even in an infinite
sample. The calculation method is based on the concept of the emergent
magnetic field. The particular case of the simplest nontrivial toroidal hopfion with
the Hopf index jQHj ¼ 1 in the cylindrical magnetic dot is considered and
dependencies of the gyrovector components on the dot sizes are calculated.
Nonzero hopfion gyrovector is important in any description of the hopfion
dynamics within the collective coordinate Thiele’s approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Magnetic hopfions are localized magnetic solitons with a nonzero 3D topological
charge (Hopf index). Herein, an analytical calculation of the magnetic hopfion
gyrovector is presented and it is shown that it does not vanish even in an infinite
sample. The calculation method is based on the concept of the emergent
magnetic field. The particular case of the simplest nontrivial toroidal hopfion with
the Hopf index jQHj ¼ 1 in the cylindrical magnetic dot is considered and
dependencies of the gyrovector components on the dot sizes are calculated.
Nonzero hopfion gyrovector is important in any description of the hopfion
dynamics within the collective coordinate Thiele’s approach.
charge (Hopf index). Herein, an analytical calculation of the magnetic hopfion
gyrovector is presented and it is shown that it does not vanish even in an infinite
sample. The calculation method is based on the concept of the emergent
magnetic field. The particular case of the simplest nontrivial toroidal hopfion with
the Hopf index jQHj ¼ 1 in the cylindrical magnetic dot is considered and
dependencies of the gyrovector components on the dot sizes are calculated.
Nonzero hopfion gyrovector is important in any description of the hopfion
dynamics within the collective coordinate Thiele’s approach.
313.
R Mehta, Mathieu Moalic, Maciej Krawczyk, S Saha
Tunability of spin-wave spectra in a 2D triangular shaped magnonic fractals Journal Article
In: Journal of Physics: Condensed Matter, vol. 35, no. 32, 2023.
@article{mehta_tuna_23,
title = {Tunability of spin-wave spectra in a 2D triangular shaped magnonic fractals},
author = {R Mehta and Mathieu Moalic and Maciej Krawczyk and S Saha},
doi = {10.1088/1361-648X/acd15f},
year = {2023},
date = {2023-05-12},
urldate = {2023-05-12},
journal = {Journal of Physics: Condensed Matter},
volume = {35},
number = {32},
abstract = {Reprogramming the structure of the magnonic bands during their operation is important for controlling spin waves in magnonic devices. Here, we report the tunability of the spin-wave spectra for a triangular shaped deterministic magnonic fractal, which is known as Sierpinski triangle by solving the Landau–Lifshitz–Gilbert equation using a micromagnetic simulations. The spin-wave dynamics change significantly with the variation of iteration number. A wide frequency gap is observed for a structure with an iteration number exceeding some value and a plenty of mini-frequency bandgaps at structures with high iteration number. The frequency gap could be controlled by varying the strength of the magnetic field. A sixfold symmetry in the frequency gap is observed with the variation of the azimuthal angle of the external magnetic field. The spatial distributions of the spin-wave modes allow to identify the bands surrounding the gap. The observations are important for the application of magnetic fractals as a reconfigurable aperiodic magnonic crystals.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Reprogramming the structure of the magnonic bands during their operation is important for controlling spin waves in magnonic devices. Here, we report the tunability of the spin-wave spectra for a triangular shaped deterministic magnonic fractal, which is known as Sierpinski triangle by solving the Landau–Lifshitz–Gilbert equation using a micromagnetic simulations. The spin-wave dynamics change significantly with the variation of iteration number. A wide frequency gap is observed for a structure with an iteration number exceeding some value and a plenty of mini-frequency bandgaps at structures with high iteration number. The frequency gap could be controlled by varying the strength of the magnetic field. A sixfold symmetry in the frequency gap is observed with the variation of the azimuthal angle of the external magnetic field. The spatial distributions of the spin-wave modes allow to identify the bands surrounding the gap. The observations are important for the application of magnetic fractals as a reconfigurable aperiodic magnonic crystals.
312.
J M Flores-Camacho, Bivas Rana, R E Balderas-Navarro, A Lastras-Martínez, Y Otani, J Puebla
Mid-infrared optical properties of non-magnetic-metal/CoFeB/MgO heterostructures Journal Article
In: Journal of Physics D: Applied Physics, vol. 56, no. 31, 2023.
@article{flores2023mid,
title = {Mid-infrared optical properties of non-magnetic-metal/CoFeB/MgO heterostructures},
author = {J M Flores-Camacho and Bivas Rana and R E Balderas-Navarro and A Lastras-Martínez and Y Otani and J Puebla},
doi = {10.1088/1361-6463/acd00f},
year = {2023},
date = {2023-05-09},
urldate = {2023-05-09},
journal = {Journal of Physics D: Applied Physics},
volume = {56},
number = {31},
abstract = {We report on the optical characterization of non-magnetic metal (NM)/ferromagnetic (Co20Fe60B20)/MgO heterostructures and interfaces by using mid infrared (MIR) spectroscopic ellipsometry at room temperature. We extracted for the MIR range the dielectric function (DF) of Co20Fe60B20, that is lacking in literature, from a multisample analysis. From the optical modeling of the heterostructures we detected and determined the dielectric tensor properties of a two-dimensional electron gas (2DEG) forming at the NM and the CoFeB interface. These properties comprise independent Drude parameters for the in-plane and out-of plane tensor components, with the latter having an epsilon-near-zero frequency within our working spectral range. A feature assigned to spin–orbit coupling (SOC) is identified. Furthermore, it is found that both, the interfacial properties, 2DEG Drude parameters and SOC strength, and the apparent DF of the MgO layer depend on the type of the underlying NM, namely, Pt, W, or Cu. The results reported here should be useful in tailoring novel phenomena in such types of heterostructures by assessing their optical response noninvasively, complementing existing characterization tools such as angle-resolved photoemission spectroscopy, and those related to electron/spin transport.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report on the optical characterization of non-magnetic metal (NM)/ferromagnetic (Co20Fe60B20)/MgO heterostructures and interfaces by using mid infrared (MIR) spectroscopic ellipsometry at room temperature. We extracted for the MIR range the dielectric function (DF) of Co20Fe60B20, that is lacking in literature, from a multisample analysis. From the optical modeling of the heterostructures we detected and determined the dielectric tensor properties of a two-dimensional electron gas (2DEG) forming at the NM and the CoFeB interface. These properties comprise independent Drude parameters for the in-plane and out-of plane tensor components, with the latter having an epsilon-near-zero frequency within our working spectral range. A feature assigned to spin–orbit coupling (SOC) is identified. Furthermore, it is found that both, the interfacial properties, 2DEG Drude parameters and SOC strength, and the apparent DF of the MgO layer depend on the type of the underlying NM, namely, Pt, W, or Cu. The results reported here should be useful in tailoring novel phenomena in such types of heterostructures by assessing their optical response noninvasively, complementing existing characterization tools such as angle-resolved photoemission spectroscopy, and those related to electron/spin transport.
311.
Andriy E Serebryannikov, D Skigin, H Hajian, E Ozbay
Wide-angle and simultaneously wideband blazing (deflection) enabling multifunctionality in metagratings comprising epsilon-near-zero materials Journal Article
In: Journal of the Optical Society of America B, vol. 40, no. 5, pp. 1340–1349, 2023.
@article{Serebryannikov:23,
title = {Wide-angle and simultaneously wideband blazing (deflection) enabling multifunctionality in metagratings comprising epsilon-near-zero materials},
author = {Andriy E Serebryannikov and D Skigin and H Hajian and E Ozbay },
url = {https://opg.optica.org/josab/abstract.cfm?URI=josab-40-5-1340},
doi = {10.1364/JOSAB.485457},
year = {2023},
date = {2023-05-01},
urldate = {2023-05-01},
journal = {Journal of the Optical Society of America B},
volume = {40},
number = {5},
pages = {1340--1349},
abstract = {This paper investigates diffractions by gratings made of a dispersive material in an epsilon-near-zero (ENZ) regime and having one-side corrugations, and those by two-component dielectric-ENZ gratings with the inner corrugations and flat outer interfaces. The goal is to achieve wideband and simultaneously wide-angle -1st order blazing (deflection) that may enable wideband spatial filtering and demultiplexing in reflection mode. Several typical scenarios are discussed, which differ in the maximum magnitude of the blazed wave and size of the blazing area observed on the frequency-incidence angle plane, as well as the contribution of the ranges of positive and negative permittivity in the vicinity of zero. The high capability of ENZ and dielectric-ENZ gratings in asymmetric reflection is demonstrated for three different levels of losses for the dispersive material.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper investigates diffractions by gratings made of a dispersive material in an epsilon-near-zero (ENZ) regime and having one-side corrugations, and those by two-component dielectric-ENZ gratings with the inner corrugations and flat outer interfaces. The goal is to achieve wideband and simultaneously wide-angle -1st order blazing (deflection) that may enable wideband spatial filtering and demultiplexing in reflection mode. Several typical scenarios are discussed, which differ in the maximum magnitude of the blazed wave and size of the blazing area observed on the frequency-incidence angle plane, as well as the contribution of the ranges of positive and negative permittivity in the vicinity of zero. The high capability of ENZ and dielectric-ENZ gratings in asymmetric reflection is demonstrated for three different levels of losses for the dispersive material.
310.
A Etesamirad, Julia Kharlan, R Rodriguez, I Barsukov, R Verba
Controlling Selection Rules for Magnon Scattering in Nanomagnets by Spatial Symmetry Breaking Journal Article
In: Physics Review Applied, vol. 19, iss. 4, no. 044087, pp. 15, 2023.
@article{PhysRevApplied.19.044087,
title = {Controlling Selection Rules for Magnon Scattering in Nanomagnets by Spatial Symmetry Breaking},
author = {A Etesamirad and Julia Kharlan and R Rodriguez and I Barsukov and R Verba},
url = {https://link.aps.org/doi/10.1103/PhysRevApplied.19.044087},
doi = {10.1103/PhysRevApplied.19.044087},
year = {2023},
date = {2023-04-27},
urldate = {2023-04-27},
journal = {Physics Review Applied},
volume = {19},
number = {044087},
issue = {4},
pages = {15},
abstract = {Nanomagnets are the building blocks of many existing and emergent spintronic technologies. The magnetization dynamics of nanomagnets is often dominated by nonlinear processes, which have been recently shown to have many surprising features and far-reaching implications for applications. Here we develop a theoretical framework uncovering the selection rules for multimagnon processes and discuss their underlying mechanisms. For its technological relevance, we focus on the degenerate three-magnon process in thin elliptical nanodisks to illustrate our findings. We parameterize the selection rules through a set of magnon interaction coefficients which we calculate using micromagnetic simulations. We postulate the selection rules and investigate how they are altered by perturbations that break the symmetry of static magnetization configuration and spatial spin-wave profiles and that can be realized by applying off-symmetry-axis or nonuniform magnetic fields. Our work provides the phenomenological understanding of the mechanics of magnon interaction as well as the formalism for determining the interaction coefficients from simulations and experimental data. Our results serve as a guide to analyze the magnon processes inherently present in spin-torque devices in order to boost their performance or to engineer a specific nonlinear response in a nanomagnet used in a neuromorphic or quantum magnonic application.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nanomagnets are the building blocks of many existing and emergent spintronic technologies. The magnetization dynamics of nanomagnets is often dominated by nonlinear processes, which have been recently shown to have many surprising features and far-reaching implications for applications. Here we develop a theoretical framework uncovering the selection rules for multimagnon processes and discuss their underlying mechanisms. For its technological relevance, we focus on the degenerate three-magnon process in thin elliptical nanodisks to illustrate our findings. We parameterize the selection rules through a set of magnon interaction coefficients which we calculate using micromagnetic simulations. We postulate the selection rules and investigate how they are altered by perturbations that break the symmetry of static magnetization configuration and spatial spin-wave profiles and that can be realized by applying off-symmetry-axis or nonuniform magnetic fields. Our work provides the phenomenological understanding of the mechanics of magnon interaction as well as the formalism for determining the interaction coefficients from simulations and experimental data. Our results serve as a guide to analyze the magnon processes inherently present in spin-torque devices in order to boost their performance or to engineer a specific nonlinear response in a nanomagnet used in a neuromorphic or quantum magnonic application.
309.
J Kisielewski, Paweł Gruszecki, Maciej Krawczyk, V Zablotskii, A Maziewski
Between waves and patterns: Spin wave freezing in films with Dzyaloshinskii-Moriya interaction Journal Article
In: Physical Review B, vol. 107, iss. 13, no. 14, pp. 134416, 2023.
@article{PhysRevB.107.134416,
title = {Between waves and patterns: Spin wave freezing in films with Dzyaloshinskii-Moriya interaction},
author = {J Kisielewski and Paweł Gruszecki and Maciej Krawczyk and V Zablotskii and A Maziewski},
doi = {10.1103/PhysRevB.107.134416},
year = {2023},
date = {2023-04-12},
urldate = {2023-04-12},
journal = {Physical Review B},
volume = {107},
number = {14},
issue = {13},
pages = {134416},
abstract = {The relationship between waves and static pattern formation is an intriguing effect and remains unexplained
in many areas of physics, including magnetism. We study the spin-wave-mediated spin reorientation transition
(SRT) in magnetic films with uniaxial magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). In
particular, we show that propagating spin waves can freeze in the SRT, causing periodic magnetic domains to
arise, which is reminiscent of the wave amplitude distribution. This process can take place under the influence of
a change in the magnetic field, but also of other parameters. Interestingly, at the SRT, DMI nonreciprocity leads
to the emergence of flowing magnetization patterns, which suggests a spontaneous breaking of translational
symmetry, and the formation of magnonic space-time crystals. The described phenomena are general and should
take place in a large family of magnetic materials. Therefore, the results should be of great importance for the
further development of spintronics and magnonics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The relationship between waves and static pattern formation is an intriguing effect and remains unexplained
in many areas of physics, including magnetism. We study the spin-wave-mediated spin reorientation transition
(SRT) in magnetic films with uniaxial magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). In
particular, we show that propagating spin waves can freeze in the SRT, causing periodic magnetic domains to
arise, which is reminiscent of the wave amplitude distribution. This process can take place under the influence of
a change in the magnetic field, but also of other parameters. Interestingly, at the SRT, DMI nonreciprocity leads
to the emergence of flowing magnetization patterns, which suggests a spontaneous breaking of translational
symmetry, and the formation of magnonic space-time crystals. The described phenomena are general and should
take place in a large family of magnetic materials. Therefore, the results should be of great importance for the
further development of spintronics and magnonics.
in many areas of physics, including magnetism. We study the spin-wave-mediated spin reorientation transition
(SRT) in magnetic films with uniaxial magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI). In
particular, we show that propagating spin waves can freeze in the SRT, causing periodic magnetic domains to
arise, which is reminiscent of the wave amplitude distribution. This process can take place under the influence of
a change in the magnetic field, but also of other parameters. Interestingly, at the SRT, DMI nonreciprocity leads
to the emergence of flowing magnetization patterns, which suggests a spontaneous breaking of translational
symmetry, and the formation of magnonic space-time crystals. The described phenomena are general and should
take place in a large family of magnetic materials. Therefore, the results should be of great importance for the
further development of spintronics and magnonics.
308.
A Deka, Bivas Rana, Y Otani, Y Fukuma
Ferromagnetic resonance excited by interfacial microwave electric field: the role of current-induced torques Journal Article
In: Journal of Physics: Condensed Matter, vol. 35, no. 21, pp. 214003, 2023.
@article{deka2023ferromagnetic,
title = {Ferromagnetic resonance excited by interfacial microwave electric field: the role of current-induced torques},
author = {A Deka and Bivas Rana and Y Otani and Y Fukuma},
doi = {10.1088/1361-648X/acc377},
year = {2023},
date = {2023-03-24},
journal = {Journal of Physics: Condensed Matter},
volume = {35},
number = {21},
pages = {214003},
abstract = {Excitation of magnetization dynamics in magnetic materials, especially in ultrathin
ferromagnetic films, is of utmost importance for developing various ultrafast spintronics
devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance
(FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received
particular attention due to several advantages, including lower power consumption. However,
several additional torques generated by unavoidable microwave current induced because of the
capacitive nature of the junctions may also contribute to the excitation of FMR apart from
electric field-induced torques. Here, we study the FMR signals excited by applying microwave
signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer
layers. Analysis of the resonance line shape and angular dependent behavior of resonance
amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA)
torque a significant contribution can also arises from spin-torques and Oersted field torques
originating from the flow of microwave current through metal-oxide junction. Surprisingly, the
overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA
torque contribution, even for a device with negligible defects. This study will be beneficial for
designing future electric field-controlled spintronics devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Excitation of magnetization dynamics in magnetic materials, especially in ultrathin
ferromagnetic films, is of utmost importance for developing various ultrafast spintronics
devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance
(FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received
particular attention due to several advantages, including lower power consumption. However,
several additional torques generated by unavoidable microwave current induced because of the
capacitive nature of the junctions may also contribute to the excitation of FMR apart from
electric field-induced torques. Here, we study the FMR signals excited by applying microwave
signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer
layers. Analysis of the resonance line shape and angular dependent behavior of resonance
amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA)
torque a significant contribution can also arises from spin-torques and Oersted field torques
originating from the flow of microwave current through metal-oxide junction. Surprisingly, the
overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA
torque contribution, even for a device with negligible defects. This study will be beneficial for
designing future electric field-controlled spintronics devices.
ferromagnetic films, is of utmost importance for developing various ultrafast spintronics
devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance
(FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received
particular attention due to several advantages, including lower power consumption. However,
several additional torques generated by unavoidable microwave current induced because of the
capacitive nature of the junctions may also contribute to the excitation of FMR apart from
electric field-induced torques. Here, we study the FMR signals excited by applying microwave
signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer
layers. Analysis of the resonance line shape and angular dependent behavior of resonance
amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA)
torque a significant contribution can also arises from spin-torques and Oersted field torques
originating from the flow of microwave current through metal-oxide junction. Surprisingly, the
overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA
torque contribution, even for a device with negligible defects. This study will be beneficial for
designing future electric field-controlled spintronics devices.
307.
Liubov Ivzhenko, A Girich, A Hrinchenko, O Yermakov
Mechanically Tunable Topological Transition and High-Directional Propagation of Surface Waves at Bilayer Hyperbolic Metasurfaces Journal Article
In: 2022 IEEE 2nd Ukrainian Microwave Week (UkrMW), pp. 214-217, 2023.
@article{10037146,
title = {Mechanically Tunable Topological Transition and High-Directional Propagation of Surface Waves at Bilayer Hyperbolic Metasurfaces},
author = {Liubov Ivzhenko and A Girich and A Hrinchenko and O Yermakov},
doi = {10.1109/UkrMW58013.2022.10037146},
year = {2023},
date = {2023-02-13},
urldate = {2023-02-13},
journal = {2022 IEEE 2nd Ukrainian Microwave Week (UkrMW)},
pages = {214-217},
abstract = {We propose simple and efficient way to control the propagation regime and direction of spoof surface plasmon-polaritons localized at bilayer hyperbolic metasurfaces. We demonstrate the photonic topological transition at the same frequency implemented with a mutual rotation of the metasurface layers. Finally, we show the tunable multidirectional in-plane canalization of surface waves adjusting by the interlayer coupling. These results discover new opportunities for the manipulation over surface waves at metasurfaces.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We propose simple and efficient way to control the propagation regime and direction of spoof surface plasmon-polaritons localized at bilayer hyperbolic metasurfaces. We demonstrate the photonic topological transition at the same frequency implemented with a mutual rotation of the metasurface layers. Finally, we show the tunable multidirectional in-plane canalization of surface waves adjusting by the interlayer coupling. These results discover new opportunities for the manipulation over surface waves at metasurfaces.
306.
J Feilhauer, Mateusz Zelent, Z Zhang, J Christensen, Michał Mruczkiewicz
Unidirectional spin-wave edge modes in magnonic crystal Journal Article
In: APL Materials, vol. 11, no. 2, pp. 021104, 2023.
@article{doi:10.1063/5.0134099,
title = {Unidirectional spin-wave edge modes in magnonic crystal},
author = {J Feilhauer and Mateusz Zelent and Z Zhang and J Christensen and Michał Mruczkiewicz},
url = { https://doi.org/10.1063/5.0134099},
doi = {10.1063/5.0134099},
year = {2023},
date = {2023-02-13},
urldate = {2023-02-13},
journal = {APL Materials},
volume = {11},
number = {2},
pages = {021104},
abstract = {We present a numerical demonstration of magnonic crystals hosting unidirectional, topologically protected edge states. The magnonic crystal is formed of dipolarly coupled Permalloy triangles. We show that due to the geometry of the block, the size of the structure can be scaled up. In addition, edge states can be found over a wide frequency range. Experimental detection of edge excitations in the considered system can be done with state-of-the-art techniques. Thus, we demonstrate a proof-of-concept magnonic Chern topological insulator nanostructure with simple geometry feasible for experimental realization. Furthermore, by tuning the strength of the perpendicular magnetic field, we induce a topological phase transition, which results in the change of direction of the topological edge state. Then, we demonstrate the magnonic switch based on this effect.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a numerical demonstration of magnonic crystals hosting unidirectional, topologically protected edge states. The magnonic crystal is formed of dipolarly coupled Permalloy triangles. We show that due to the geometry of the block, the size of the structure can be scaled up. In addition, edge states can be found over a wide frequency range. Experimental detection of edge excitations in the considered system can be done with state-of-the-art techniques. Thus, we demonstrate a proof-of-concept magnonic Chern topological insulator nanostructure with simple geometry feasible for experimental realization. Furthermore, by tuning the strength of the perpendicular magnetic field, we induce a topological phase transition, which results in the change of direction of the topological edge state. Then, we demonstrate the magnonic switch based on this effect.
305.
Paweł Gruszecki, J Kisielewski
Influence of Dzyaloshinskii–Moriya interaction and perpendicular anisotropy on spin waves propagation in stripe domain patterns and spin spirals Journal Article
In: Scientific Reports, vol. 13, no. 1218, 2023.
@article{gruszecki_influence_23,
title = {Influence of Dzyaloshinskii–Moriya interaction and perpendicular anisotropy on spin waves propagation in stripe domain patterns and spin spirals},
author = {Paweł Gruszecki and J Kisielewski
},
doi = {https://doi.org/10.1038/s41598-023-28271-2},
year = {2023},
date = {2023-01-21},
journal = {Scientific Reports},
volume = {13},
number = {1218},
abstract = {Texture-based magnonics focuses on the utilization of spin waves in magnetization textures to process information. Using micromagnetic simulations, we study how (1) the dynamic magnetic susceptibility, (2) dispersion relations, and (3) the equilibrium magnetic configurations in periodic magnetization textures in a ultrathin ferromagnetic film in remanence depend on the values of the Dzyaloshinskii–Moriya interaction and the perpendicular magnetocrystalline anisotropy. We observe that for large Dzyaloshinskii–Moriya interaction values, spin spirals with periods of tens of nanometers are the preferred state; for small Dzyaloshinskii–Moriya interaction values and large anisotropies, stripe domain patterns with over a thousand times larger period are preferable. We observe and explain the selectivity of the excitation of resonant modes by a linearly polarized microwave field. We study the propagation of spin waves along and perpendicular to the direction of the periodicity. For propagation along the direction of the periodicity, we observe a bandgap that closes and reopens, which is accompanied by a swap in the order of the bands. For waves propagating in the perpendicular direction, some modes can be used for unidirectional channeling of spin waves. Overall, our findings are promising in sensing and signal processing applications and explain the fundamental properties of periodic magnetization textures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Texture-based magnonics focuses on the utilization of spin waves in magnetization textures to process information. Using micromagnetic simulations, we study how (1) the dynamic magnetic susceptibility, (2) dispersion relations, and (3) the equilibrium magnetic configurations in periodic magnetization textures in a ultrathin ferromagnetic film in remanence depend on the values of the Dzyaloshinskii–Moriya interaction and the perpendicular magnetocrystalline anisotropy. We observe that for large Dzyaloshinskii–Moriya interaction values, spin spirals with periods of tens of nanometers are the preferred state; for small Dzyaloshinskii–Moriya interaction values and large anisotropies, stripe domain patterns with over a thousand times larger period are preferable. We observe and explain the selectivity of the excitation of resonant modes by a linearly polarized microwave field. We study the propagation of spin waves along and perpendicular to the direction of the periodicity. For propagation along the direction of the periodicity, we observe a bandgap that closes and reopens, which is accompanied by a swap in the order of the bands. For waves propagating in the perpendicular direction, some modes can be used for unidirectional channeling of spin waves. Overall, our findings are promising in sensing and signal processing applications and explain the fundamental properties of periodic magnetization textures.
2022
304.
Mathieu Moalic, Maciej Krawczyk, Mateusz Zelent
Spin-wave spectra in antidot lattice with inhomogeneous perpendicular magnetic anisotropy Journal Article
In: Journal of Applied Physics, vol. 132, pp. 213901 , 2022.
@article{Moalic_antidot_lattice,
title = {Spin-wave spectra in antidot lattice with inhomogeneous perpendicular magnetic anisotropy},
author = {Mathieu Moalic and Maciej Krawczyk and Mateusz Zelent},
doi = {10.1063/5.0128621},
year = {2022},
date = {2022-12-01},
urldate = {2022-12-01},
journal = {Journal of Applied Physics},
volume = {132},
pages = {213901 },
abstract = {Magnonic crystals are structures with periodically varied magnetic properties that are used to control collective spin-wave excitations. With micromagnetic simulations, we study spin-wave spectra in a 2D antidot lattice based on a multilayered thin film with perpendicular magnetic anisotropy (PMA). We show that the modification of the PMA near the antidot edges introduces interesting changes to the spin-wave spectra, even in a fully saturated state. In particular, the spectra split into two types of excitations: bulk modes with amplitude concentrated in a homogeneous part of the antidot lattice and edge modes with an amplitude localized in the rims of reduced PMA at the antidot edges. Their dependence on the geometrical or material parameters is distinct, but at resonance conditions fulfilled, we found strong hybridization between bulk and radial edge modes. Interestingly, the hybridization between the fundamental modes in bulk and rim is of magnetostatic origin, but the exchange interactions determine the coupling between higher-order radial rim modes and the fundamental bulk mode of the antidot lattice.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Magnonic crystals are structures with periodically varied magnetic properties that are used to control collective spin-wave excitations. With micromagnetic simulations, we study spin-wave spectra in a 2D antidot lattice based on a multilayered thin film with perpendicular magnetic anisotropy (PMA). We show that the modification of the PMA near the antidot edges introduces interesting changes to the spin-wave spectra, even in a fully saturated state. In particular, the spectra split into two types of excitations: bulk modes with amplitude concentrated in a homogeneous part of the antidot lattice and edge modes with an amplitude localized in the rims of reduced PMA at the antidot edges. Their dependence on the geometrical or material parameters is distinct, but at resonance conditions fulfilled, we found strong hybridization between bulk and radial edge modes. Interestingly, the hybridization between the fundamental modes in bulk and rim is of magnetostatic origin, but the exchange interactions determine the coupling between higher-order radial rim modes and the fundamental bulk mode of the antidot lattice.
303.
Justyna Rychły, J Walowski, C Denker, T Tubandt, M Münzenberg, Jarosław W Kłos
Shaping the spin wave spectra of planar 1D magnonic crystals by the geometrical constraints Journal Article
In: Scientific Reports, vol. 12, no. 20678 , 2022.
@article{Rychly_2022_shaping_sw,
title = {Shaping the spin wave spectra of planar 1D magnonic crystals by the geometrical constraints},
author = {Justyna Rychły and J Walowski and C Denker and T Tubandt and M Münzenberg and Jarosław W Kłos },
doi = {https://doi.org/10.1038/s41598-022-24969-x},
year = {2022},
date = {2022-11-30},
urldate = {2022-11-30},
journal = {Scientific Reports},
volume = {12},
number = {20678 },
abstract = {We present experimental and numerical studies demonstrating the influence of geometrical parameters on the fundamental spin-wave mode in planar 1D magnonic crystals. The investigated magnonic crystals consist of flat stripes separated by air gaps. The adjustment of geometrical parameters allows tailoring of the spin-wave frequencies. The width of stripes and the width of gaps between them affect spin-wave frequencies in two ways. First, directly by geometrical constraints confining the spin waves inside the stripes. Second, indirectly by spin-wave pinning, freeing the spin waves to a different extent on the edges of stripes. Experimentally, the fundamental spin-wave mode frequencies are measured using an all-optical pump-probe time-resolved magneto-optical Kerr-effect setup. Our studies address the problem of spin-wave confinement and spin-wave dipolar pinning in an array of coupled stripes. We show that the frequency of fundamental mode can be tuned to a large extent by adjusting the width of the stripes and the width of gaps between them.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present experimental and numerical studies demonstrating the influence of geometrical parameters on the fundamental spin-wave mode in planar 1D magnonic crystals. The investigated magnonic crystals consist of flat stripes separated by air gaps. The adjustment of geometrical parameters allows tailoring of the spin-wave frequencies. The width of stripes and the width of gaps between them affect spin-wave frequencies in two ways. First, directly by geometrical constraints confining the spin waves inside the stripes. Second, indirectly by spin-wave pinning, freeing the spin waves to a different extent on the edges of stripes. Experimentally, the fundamental spin-wave mode frequencies are measured using an all-optical pump-probe time-resolved magneto-optical Kerr-effect setup. Our studies address the problem of spin-wave confinement and spin-wave dipolar pinning in an array of coupled stripes. We show that the frequency of fundamental mode can be tuned to a large extent by adjusting the width of the stripes and the width of gaps between them.
302.
Andriy E Serebryannikov, A Lakhtakia, E Ozbay
In: Opt. Mater. Express, vol. 12, no. 12, pp. 4594–4605, 2022.
@article{Serebryannikov:22,
title = {Thermally switchable, bifunctional, scalable, mid-infrared metasurfaces with VO2 grids capable of versatile polarization manipulation and asymmetric transmission},
author = {Andriy E Serebryannikov and A Lakhtakia and E Ozbay},
url = {https://opg.optica.org/ome/abstract.cfm?URI=ome-12-12-4594},
doi = {10.1364/OME.465468},
year = {2022},
date = {2022-11-16},
journal = {Opt. Mater. Express},
volume = {12},
number = {12},
pages = {4594--4605},
abstract = {We conceptualized three-array scalable bifunctional metasurfaces comprising only three thin strip grids and numerically determined their characteristics in the mid-infrared spectral regime for switchable operation scenarios involving polarization manipulation and related diodelike asymmetric transmission (AT) as one of two functionalities. A few or all of the grids were taken to be made of VO2, a bifunctionality-enabling phase-change material; there are no layers and/or meta-atoms comprising simultaneously both metal and VO2. For each proposed metasurface, two effective structures and, therefore, two different functionalities exist, corresponding to the metallic and insulating phases of VO2. The achieved scenarios of functionality switching significantly depend on the way in which VO2 is incorporated into the metasurface. Switchable bands of polarization manipulation are up to 40 THz wide. The AT band can be modulated when Fabry-Perot (anti-) resonances come into play. Besides, transmission regimes with the cross-polarized component insensitive to VO2 phase change are possible, as well as the ones with all co- and cross-polarized components having the same magnitude for both linear polarizations of the incident wave.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We conceptualized three-array scalable bifunctional metasurfaces comprising only three thin strip grids and numerically determined their characteristics in the mid-infrared spectral regime for switchable operation scenarios involving polarization manipulation and related diodelike asymmetric transmission (AT) as one of two functionalities. A few or all of the grids were taken to be made of VO2, a bifunctionality-enabling phase-change material; there are no layers and/or meta-atoms comprising simultaneously both metal and VO2. For each proposed metasurface, two effective structures and, therefore, two different functionalities exist, corresponding to the metallic and insulating phases of VO2. The achieved scenarios of functionality switching significantly depend on the way in which VO2 is incorporated into the metasurface. Switchable bands of polarization manipulation are up to 40 THz wide. The AT band can be modulated when Fabry-Perot (anti-) resonances come into play. Besides, transmission regimes with the cross-polarized component insensitive to VO2 phase change are possible, as well as the ones with all co- and cross-polarized components having the same magnitude for both linear polarizations of the incident wave.
301.
A Girich, Liubov Ivzhenko, A Hrinchenko, S Tarapov, O Yermakov
Manipulation Over Surface Waves in Bilayer Hyperbolic Metasurfaces: Topological Transition and Multidirectional Canalization Journal Article
In: IEEE Microwave and Wireless Components Letters, pp. 1 - 4, 2022.
@article{Ivzhenko_2022_manipulation,
title = {Manipulation Over Surface Waves in Bilayer Hyperbolic Metasurfaces: Topological Transition and Multidirectional Canalization},
author = {A Girich and Liubov Ivzhenko and A Hrinchenko and S Tarapov and O Yermakov},
doi = {10.1109/LMWC.2022.3215016},
year = {2022},
date = {2022-10-27},
urldate = {2022-10-27},
journal = {IEEE Microwave and Wireless Components Letters},
pages = {1 - 4},
abstract = {Spoof surface plasmon-polariton is a type of surface wave (SW) propagating at the artificially engineered structures in microwave and terahertz ranges. These SWs are highly important in planar photonic and on-chip devices, integrated circuits, lenses, sensors, and antennas applications. However, it is still a challenge to control the propagation regime of such SWs including the wavefront shapes and propagation directions. In this letter, we study the SWs in bilayer hyperbolic metasurfaces and show that the interplay between two layers allows them to manage their regime of propagation. We demonstrate the switching between the angle and number of propagation directions of SWs at the same frequency. Finally, we demonstrate experimentally the tunable multidirectional in-plane canalization of SWs by adjusting the directions of their propagation within the angular range from 0 ∘ to 12.8 ∘ . The discovered rotation-mediated interlayer coupling of hyperbolic metasurfaces paves the way toward efficient in-plane transfer of localized electromagnetic signals.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Spoof surface plasmon-polariton is a type of surface wave (SW) propagating at the artificially engineered structures in microwave and terahertz ranges. These SWs are highly important in planar photonic and on-chip devices, integrated circuits, lenses, sensors, and antennas applications. However, it is still a challenge to control the propagation regime of such SWs including the wavefront shapes and propagation directions. In this letter, we study the SWs in bilayer hyperbolic metasurfaces and show that the interplay between two layers allows them to manage their regime of propagation. We demonstrate the switching between the angle and number of propagation directions of SWs at the same frequency. Finally, we demonstrate experimentally the tunable multidirectional in-plane canalization of SWs by adjusting the directions of their propagation within the angular range from 0 ∘ to 12.8 ∘ . The discovered rotation-mediated interlayer coupling of hyperbolic metasurfaces paves the way toward efficient in-plane transfer of localized electromagnetic signals.