M.Sc. Krzysztof Sobucki
- Tel: +48 61 829 5192
- Loc: wing G, second floor, room 276
- Email: krzsob@amu.edu.pl
Scientific degrees
MSc in Physics – 2020
Research interests
Keywords: magnonics, numerical simulations, spintronics, magnetism
I carry out numerical simulations of spin waves propagation in magnetic media. I use Comsol Multiphysics environment and Mumax3 in my work.
Research stays
02-07.2020 – Internship in IMEC Leuven
Projects
1. | Krzysztof Sobucki Exploiting resonance effects in ferromagnetic nanoresonators towards magnonic spacetime metasurfaces 2023 - 2026, (NCN PRELUDIUM-2, No. 2022/45/N/ST3/01844, budget: 209 925 PLN). @misc{Sobucki_mata, title = {Exploiting resonance effects in ferromagnetic nanoresonators towards magnonic spacetime metasurfaces}, author = {Krzysztof Sobucki}, url = {https://isik.amu.edu.pl/spacetime-metasurfaces/}, year = {2026}, date = {2026-02-14}, abstract = {Modern information processing and transmission technologies are almost entirely based on electronics, i.e., using electrical charges as information carriers. Although electronics has many advantages, it is also burdened with many disadvantages that severely limit the further development of this technology. These drawbacks include, e.g., the limits of miniaturisation of electronic circuits and the Joule heat generation during the transmission of electrical charges in conductors. Therefore, it is essential to develop alternative technologies to electronics, which could support the currently used technologies or even replace them. One of the fields of physics currently being developed in this regard is magnonics, the science of spin-wave propagation. Spin waves have unusual properties, unattainable by electromagnetic waves used in photonics and broader microwave technologies. They are characterised by much shorter wavelengths than their electromagnetic counterparts at the same frequencies. In addition, spin waves do not carry any charge or mass. Therefore significantly less energy is required to transmit information when spin waves are used, than when electric charges are used. The same quantities describe spin waves as other waves, i.e., amplitude, wavelength, and phase. Therefore, using spin waves in functional magnonic devices involves finding means to operate their parameters similarly to other known wave devices. Our project will focus on investigating the resonance effects of spin waves incident on magnonic Gires- Tournois type interferometers. These interferometers modulate the phase and amplitude of the waves reflected from them and are ideal for manipulating spin waves. We will begin our study by describing the reflection of spin waves from a uniformly magnetised interferometer. We will then study the phenomenon of inelastic scattering of spin waves on mode located in a uniformly magnetised resonator of a Gires-Tournois interferometer, which belongs to the group of nonlinear phenomena. We will then study non-uniformly magnetised resonators in the form of alternating magnetic domains with different magnetisation directions and their influence on spin-wave propagation in the interferometer environment. In the last phase of the project, we will gather all the knowledge from the previous work stages to design a stable magnonic spacetime metasurface. A meta-surface is a system component with dimensions much smaller than the wavelength, which modulates the wave parameters in a strictly man-made way. This project will propose a spacetime version of a magnonic meta-surface that is characterised by a continuous change of magnetisation direction in both time and space. The final goal of this project is to describe the possibility of using such a meta-surface as a magnetic resonator texture in an interferometer to modulate the parameters of spin waves reflected from a Gires-Tournois interferometer. Our project is the first step toward designing a new type of magnonic devices based on spin-wave modulation using resonant effects and spacetime meta-surfaces. These devices may become the basis for more complex information transmission and processing systems, which will be characterised by significantly lower energy consumption than currently used electronic systems. Thus, our project may contribute to the development of new technologies reducing energy consumption in information technologies.}, howpublished = {2023}, note = {NCN PRELUDIUM-2, No. 2022/45/N/ST3/01844, budget: 209 925 PLN}, keywords = {}, pubstate = {published}, tppubtype = {misc} } Modern information processing and transmission technologies are almost entirely based on electronics, i.e., using electrical charges as information carriers. Although electronics has many advantages, it is also burdened with many disadvantages that severely limit the further development of this technology. These drawbacks include, e.g., the limits of miniaturisation of electronic circuits and the Joule heat generation during the transmission of electrical charges in conductors. Therefore, it is essential to develop alternative technologies to electronics, which could support the currently used technologies or even replace them. One of the fields of physics currently being developed in this regard is magnonics, the science of spin-wave propagation. Spin waves have unusual properties, unattainable by electromagnetic waves used in photonics and broader microwave technologies. They are characterised by much shorter wavelengths than their electromagnetic counterparts at the same frequencies. In addition, spin waves do not carry any charge or mass. Therefore significantly less energy is required to transmit information when spin waves are used, than when electric charges are used. The same quantities describe spin waves as other waves, i.e., amplitude, wavelength, and phase. Therefore, using spin waves in functional magnonic devices involves finding means to operate their parameters similarly to other known wave devices. Our project will focus on investigating the resonance effects of spin waves incident on magnonic Gires- Tournois type interferometers. These interferometers modulate the phase and amplitude of the waves reflected from them and are ideal for manipulating spin waves. We will begin our study by describing the reflection of spin waves from a uniformly magnetised interferometer. We will then study the phenomenon of inelastic scattering of spin waves on mode located in a uniformly magnetised resonator of a Gires-Tournois interferometer, which belongs to the group of nonlinear phenomena. We will then study non-uniformly magnetised resonators in the form of alternating magnetic domains with different magnetisation directions and their influence on spin-wave propagation in the interferometer environment. In the last phase of the project, we will gather all the knowledge from the previous work stages to design a stable magnonic spacetime metasurface. A meta-surface is a system component with dimensions much smaller than the wavelength, which modulates the wave parameters in a strictly man-made way. This project will propose a spacetime version of a magnonic meta-surface that is characterised by a continuous change of magnetisation direction in both time and space. The final goal of this project is to describe the possibility of using such a meta-surface as a magnetic resonator texture in an interferometer to modulate the parameters of spin waves reflected from a Gires-Tournois interferometer. Our project is the first step toward designing a new type of magnonic devices based on spin-wave modulation using resonant effects and spacetime meta-surfaces. These devices may become the basis for more complex information transmission and processing systems, which will be characterised by significantly lower energy consumption than currently used electronic systems. Thus, our project may contribute to the development of new technologies reducing energy consumption in information technologies. |
Publication
2024 |
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6. | Julia Kharlan, Krzysztof Sobucki, Krzysztof Szulc, Sara Memarzadeh, Jarosław W. Kłos Spin-wave confinement in a hybrid superconductor-ferrimagnet nanostructure Phys. Rev. Appl., 21 , 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://link.aps.org/doi/10.1103/PhysRevApplied.21.064007}, doi = {10.1103/PhysRevApplied.21.064007}, year = {2024}, date = {2024-06-05}, journal = {Phys. Rev. Appl.}, volume = {21}, pages = {064007}, publisher = {American Physical Society}, 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. |
2023 |
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5. | 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 Nano Letters, 23 (15), pp. 6979-6984, 2023, (PMID: 37523860). @article{doi:10.1021/acs.nanolett.3c01592, 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}, journal = {Nano Letters}, volume = {23}, number = {15}, pages = {6979-6984}, 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.}, note = {PMID: 37523860}, 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. |
4. | Wojciech Śmigaj, Krzysztof Sobucki, Paweł Gruszecki, Maciej Krawczyk Modal approach to modeling spin wave scattering Phys. Rev. B, 108 , 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 = {2023-07-01}, journal = {Phys. Rev. B}, volume = {108}, pages = {014418}, publisher = {American Physical Society}, 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. |
2022 |
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3. | Krzysztof Sobucki, Maciej Krawczyk, Elena V. Tartakovskaya, Piotr Graczyk Magnon spectrum of Bloch hopfion beyond ferromagnetic resonance APL Materials, 10 (9), pp. 091103, 2022. @article{doi:10.1063/5.0100484, title = {Magnon spectrum of Bloch hopfion beyond ferromagnetic resonance}, author = {Krzysztof Sobucki and Maciej Krawczyk and Elena V. Tartakovskaya and Piotr Graczyk}, url = {https://doi.org/10.1063/5.0100484}, doi = {10.1063/5.0100484}, year = {2022}, date = {2022-09-08}, journal = {APL Materials}, volume = {10}, number = {9}, pages = {091103}, abstract = {With the development of new nanofabrication technologies and measurement techniques, the interest of researchers is moving toward 3D structures and 3D magnetization textures. Special attention is paid to the topological magnetization textures, particularly hopfions. In this paper, we investigate the magnetization dynamics of the hopfion through the numerical solution of the eigenvalue problem. We show that the spectrum of spin-wave modes of the hopfion is much richer than those attainable in ferromagnetic resonance experiments or time-domain simulations reported so far. We identified four groups of modes that differ in the character of oscillations (clockwise or counter-clockwise rotation sense), the position of an average amplitude localization along the radial direction, and different oscillations in the vertical cross section. The knowledge of the full spin-wave spectrum shall help in hopfion identification, understanding of the interaction between spin waves and hopfion dynamics as well as the development of the potential of hopfion in spintronic and magnonic applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } With the development of new nanofabrication technologies and measurement techniques, the interest of researchers is moving toward 3D structures and 3D magnetization textures. Special attention is paid to the topological magnetization textures, particularly hopfions. In this paper, we investigate the magnetization dynamics of the hopfion through the numerical solution of the eigenvalue problem. We show that the spectrum of spin-wave modes of the hopfion is much richer than those attainable in ferromagnetic resonance experiments or time-domain simulations reported so far. We identified four groups of modes that differ in the character of oscillations (clockwise or counter-clockwise rotation sense), the position of an average amplitude localization along the radial direction, and different oscillations in the vertical cross section. The knowledge of the full spin-wave spectrum shall help in hopfion identification, understanding of the interaction between spin waves and hopfion dynamics as well as the development of the potential of hopfion in spintronic and magnonic applications. |
2. | Krzysztof Sobucki, Paweł Gruszecki, Justyna Rychły, Maciej Krawczyk IEEE Transactions on Magnetics, 58 (2), pp. 1-5, 2022, ISSN: 1941-0069. @article{9450803, title = {Control of the Phase of Reflected Spin Waves From Magnonic Gires–Tournois Interferometer of Subwavelength Width}, author = {Krzysztof Sobucki and Paweł Gruszecki and Justyna Rychły and Maciej Krawczyk}, doi = {10.1109/TMAG.2021.3088298}, issn = {1941-0069}, year = {2022}, date = {2022-01-20}, journal = {IEEE Transactions on Magnetics}, volume = {58}, number = {2}, pages = {1-5}, abstract = {The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors. |
2021 |
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1. | Krzysztof Sobucki, Wojciech Śmigaj, Justyna Rychły, Maciej Krawczyk, Paweł Gruszecki Sci. Rep., 11 (1), pp. 4428, 2021, ISSN: 2045-2322. @article{sobucki_resonant_2021, title = {Resonant subwavelength control of the phase of spin waves reflected from a Gires–Tournois interferometer}, author = {Krzysztof Sobucki and Wojciech Śmigaj and Justyna Rychły and Maciej Krawczyk and Paweł Gruszecki}, url = {https://www.nature.com/articles/s41598-021-83307-9}, doi = {10.1038/s41598-021-83307-9}, issn = {2045-2322}, year = {2021}, date = {2021-02-24}, urldate = {2021-02-25}, journal = {Sci. Rep.}, volume = {11}, number = {1}, pages = {4428}, abstract = {Subwavelength resonant elements are essential building blocks of metamaterials and metasurfaces, which have revolutionized photonics. Despite similarities between different wave phenomena, other types of interactions can make subwavelength coupling significantly distinct; its investigation in their context is therefore of interest both from the physics and applications perspective. In this work, we demonstrate a fully magnonic Gires–Tournois interferometer based on a subwavelength resonator made of a narrow ferromagnetic stripe lying above the edge of a ferromagnetic film. The bilayer formed by the stripe and the film underneath supports two propagative spin-wave modes, one strongly coupled with spin waves propagating in the rest of the film and another almost completely reflected at the ends of the bilayer. When the Fabry–Perot resonance conditions for this mode are satisfied, the weak coupling between both modes is sufficient to achieve high sensitivity of the phase of waves reflected from the resonator to the stripe width and, more interestingly, also to the stripe-film separation. Such spin-wave phase manipulation capabilities are a prerequisite for the design of spin-wave metasurfaces and may stimulate development of magnonic logic devices and sensors detecting magnetic nanoparticles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Subwavelength resonant elements are essential building blocks of metamaterials and metasurfaces, which have revolutionized photonics. Despite similarities between different wave phenomena, other types of interactions can make subwavelength coupling significantly distinct; its investigation in their context is therefore of interest both from the physics and applications perspective. In this work, we demonstrate a fully magnonic Gires–Tournois interferometer based on a subwavelength resonator made of a narrow ferromagnetic stripe lying above the edge of a ferromagnetic film. The bilayer formed by the stripe and the film underneath supports two propagative spin-wave modes, one strongly coupled with spin waves propagating in the rest of the film and another almost completely reflected at the ends of the bilayer. When the Fabry–Perot resonance conditions for this mode are satisfied, the weak coupling between both modes is sufficient to achieve high sensitivity of the phase of waves reflected from the resonator to the stripe width and, more interestingly, also to the stripe-film separation. Such spin-wave phase manipulation capabilities are a prerequisite for the design of spin-wave metasurfaces and may stimulate development of magnonic logic devices and sensors detecting magnetic nanoparticles. |