FluMag: Fluxons and Magnons in hybrid nanostuctures

Tile of the project

Low-loss current- and flux quanta-controlled magnonics

Call, grant No

OPUS22+LAP, National Science Center – Poland, 2021/43/I/ST3/00550

Start date, end date

January 2, 2023 — January 1, 2026

Budget

1 042 994,00 PLN (for Polish side)

Abstract

Magnonics – the study of spin waves, which are precessional excitations of spins in magnetic materials – is one of the most rapidly developing research fields of modern magnetism. Covering a wide frequency range from sub-GHz to tens of THz and being free from the translational motion of electrons and Joule heating, spin waves are promising candidates for realizing novel, highly efficient wave-based computing concepts. While magnonics has traditionally been a room-temperature research discipline, the current great interest in hybrid systems for quantum computing requires the operation magnonic conduits at low temperatures and in environments of superconducting circuits. In this project, we are going to extend the functionalities of magnonic devices by controlling them with stray fields of superconductors.

Ferromagnetism (F) and superconductivity (S) belong to the most fundamental phenomena in condensed matter physics. Due to incompatible spin orders and antagonistic responses to an external magnetic field, their combination gives rise to numerous novel phenomena. However, the coexistence of F and S in bulk systems remains a rare circumstance peculiar to complex compounds. At the same time, the coexistence of S and F can be readily achieved in artificial ferromagnet/superconductor (F/S) heterostructures. In this regard, F/S hybrid structures can be classified either as proximity-coupled (i.e., electrically connected) or as stray-field-coupled (i.e., electrically insulated).

The project FulMag is formulated to scrutinize the physics of spin waves in electrically insulated F/S heterostructures where the interplay of spin-wave dynamics in a ferromagnet with stray fields produced by eddy currents in a superconductor can be used to explore novel magnonic functionalities in the emerging domain of cryogenic magnonics.

We will conceive theoretical foundations of the spin-wave dynamics in F/S hybrid structures and elaborate novel concepts for the excitation, manipulation, and detection of spin waves, which are beyond the reach of traditional magnonic approaches. The focus will be pointed towards cryogenic magnonic nano-devices operating preferably in the short-wavelength (exchange) spin-wave regime. Their realization will be underpinned by the fundamental physical phenomena of Meissner screening and the Cherenkov radiation of magnons originating from moving magnetic flux quanta (Abrikosov vortices). A complete and multidisciplinary theoretical description, encompassing finite-element micromagnetic simulations in conjunction with the state-of-the-art phenomenological models relying upon the Landau-Lifschitz-Gilbert equation for dipole-exchange spin-waves and the London equations or Ginzburg-Landau model of superconductivity, will allow us to design F/S hybrids with targeted functionalities. We are going to use the stray field generated by the superconducting pattern to confine and guide the spin waves in a homogeneous ferromagnetic layer. We are planning to investigate spin-wave couplers realizing the non-reciprocal spin-wave transmission/reflection and graded-index structures controlling the spin-wave refraction. Device prototypes will be examined at microwave frequencies up to 70 GHz, vector magnetic fields up to 9 T, temperatures down to 10 mK, and by time- and spatially-resolved optical spectroscopy methods. The project results will have a great impact on the domains of microwave magnetism, superconductivity, and emerging magnon-based quantum technologies.

The three Partner Teams of researchers gathered around this Polish-German-Czech collaborative project constitute a rich panel of complementary expertise in theoretical and experimental physics of spin waves, superconductivity, advanced nanofabrication as well as microwave and optical spectroscopy methods. The Polish Team is led by Jarosław Kłos from the Adam Mickiewicz University, Poznań (>>>), the Austrian Team is by Oleksandr Dobrovolskiy from the Technical University in Braunschweig (>>>) and the Czech Team by Michal Urbanek from the Central European Institute of Technology, Brno (>>>).

State of the art for Superconducting/Ferromagnetic hybrids. (a) Enhancement of nonlinear spin wave dynamics in F/S bi-layer, after [1]. The spectrum of magnetostatic surface spin waves is strongly modified due to the presence of nonlinear response of superconducting subsystem on stray magnetic fields, related to the transition of S to vortex state. (b) FMR line-broadening and field-redshift of an F/S bilayer upon transition to the S state, after [2]. (c) Magnonic metamaterial based on F/S hybridization, after [3]: Patterned Py films are placed onto a coplanar waveguide made of Nb. Experimental geometry (d) and magnon transmission spectrum (e) a Py/Nb bilayer, after [4]. Spin waves are excited by antenna 1, propagate through the Py waveguide, and are detected by antenna 2. The Bloch-like band structure in the spectrum of spin waves appears due to their scattering on the vortex lattice. (f) Prediction for the Cherenkov excitation of magnons by fast-moving fluxons, after [5]. Moving vortices excite magnetic moments shown by purple arrows (top). This additional dissipation results in current peaks in the current-voltage curve (bottom). An additional magnetic (M) viscous force adds up to the Bardeen-Stephen (BS) viscosity, resulting in a voltage drop for currents above Ion corresponding to some threshold vortex velocity vc.

Research tasks

Theoretical studies of spin wave in ferromagnet/Meissner-state-superconductor hybrids
Theoretical models for Landau-Lifshitz-Gilbert equation coupled to London equations
Investigations of coupled spin wave and vortex dynamics
Measurements and calculations of spin-wave dispersions in ferromagnet/superconductor heterostructures
Development of ferromagnet/superconductor conduits for spin-wave steering and routing – directional couplers.
Development of ferromagnet/superconductor conduits for spin-wave steering and routing – Graded-index structures
Utilization of static arrays of superconducting vortices for spin-wave excitation/detection
Generation of spin waves by moving fluxons
Phase-locked detection of spin waves by a moving lattice of fluxons with ac-shaken vortices

[1] I.A. Golovchanskiy, N.N. Abramov, V.S. Stolyarov, A.A. Golubov, V. V Ryazanov, and A. V Ustinov, Nonlinear spin waves in ferromagnetic/superconductor hybrids, J. Appl. Phys.127 (2020) 93903. doi:10.1063/1.5141793.

[2] K.-R. Jeon, C. Ciccarelli, A.J. Ferguson, H. Kurebayashi, L.F. Cohen, X. Montiel, M. Eschrig, J.W.A. Robinson, and M.G. Blamire, Enhanced spin pumping into superconductors provides evidence for superconducting pure spin currents, Nat. Mater. 17 (2018) 499–503. doi:10.1038/s41563-018-0058-9.

[3] I.A. Golovchanskiy, N.N. Abramov, V.S. Stolyarov, V. V Bolginov, V. V Ryazanov, A.A. Golubov, and A. V Ustinov, Ferromagnet/Superconductor Hybridization for Magnonic Applications, Adv. Func. Mater. 28 (2018) 1802375. doi:10.1002/adfm.201802375.

[4] O. V Dobrovolskiy, R. Sachser, T. Brächer, T. Böttcher, V. V Kruglyak, R. V Vovk, V.A. Shklovskij, M. Huth, B. Hillebrands, and A. V Chumak, Magnon-Fluxon Interaction in a Ferromagnet/Superconductor Heterostructure, Nat. Phys. 15 (2019) 477. doi:10.1038/s41567-019-0428-5.

[5] A. Shekhter, L.N. Bulaevskii, and C.D. Batista, Vortex Viscosity in Magnetic Superconductors Due to Radiation of Spin Waves, Phys. Rev. Lett.106 (2011) 37001. doi:10.1103/PhysRevLett.106.037001.

Staff – Polish team

Jaroslaw W. Klos – PI
Sara Memarzadeh – postdoc
Julia Kharlan – PhD student
Kryszof Szulc – PhD student
Gauthier Philippe – MSc student (fromer memeber)
Joana Hernandez – MSc student (fromer memeber)

Publications

2024
3.	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. Abstract \| Links \| BibTeX @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} } Close 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. Close https://link.aps.org/doi/10.1103/PhysRevApplied.21.064007 doi:10.1103/PhysRevApplied.21.064007 Close
2023
2.	Gauthier Philippe, Mathieu Moalic, Jarosław W. Kłos Unidirectional spin wave emission by traveling pair of magnetic field profiles Journal of Magnetism and Magnetic Materials, 587 , pp. 171359, 2023, ISSN: 0304-8853. Abstract \| Links \| BibTeX @article{PHILIPPE2023171359, title = {Unidirectional spin wave emission by traveling pair of magnetic field profiles}, author = {Gauthier Philippe and Mathieu Moalic and Jarosław W. Kłos}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323010090}, doi = {https://doi.org/10.1016/j.jmmm.2023.171359}, issn = {0304-8853}, year = {2023}, date = {2023-10-11}, 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} } Close 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. Close https://www.sciencedirect.com/science/article/pii/S0304885323010090 doi:https://doi.org/10.1016/j.jmmm.2023.171359 Close
1.	Grzegorz Centała, Jarosław W. Kłos Compact localized states in magnonic Lieb lattices Scientific Reports, 13 (1), pp. 12676, 2023, ISSN: 2045-2322. Abstract \| Links \| BibTeX @article{centala_compact_2023, title = {Compact localized states in magnonic Lieb lattices}, author = {Grzegorz Centała and Jarosław W. Kłos}, url = {https://www.nature.com/articles/s41598-023-39816-w}, doi = {10.1038/s41598-023-39816-w}, issn = {2045-2322}, year = {2023}, date = {2023-08-04}, urldate = {2023-08-04}, journal = {Scientific Reports}, volume = {13}, number = {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} } Close 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. Close https://www.nature.com/articles/s41598-023-39816-w doi:10.1038/s41598-023-39816-w Close

Talks and posters

SolSkyMag, San Sebastian, Spain, 19-23.06.2023
Spin wave localization induced by stray field of superconducting strip, talk
J. Kharlan, K. Szulc. J. W. Kłos
Abstract >>>

The European Conference: Physics of Magnetism, Poznań, Polska, 26-30.06.2023
Shaping the spin wave spectra of planar 1D magnonic crystals by the geometrical constraints, talk
J. Rychły-Gruszecka, J. Walowski, G. Centała, J. W. Kłos
Abstract >>>

The European Conference: Physics of Magnetism, Poznań, Polska, 26-30.06.2023
Doppler effect for spin waves: micromagnetic studies, poster
G. Philippe, M. Moalic, Jarosław W. Kłos
Abstract >>>

Joint European Magnetic Symposia (JEMS), Madryt, Hiszpania, 27.08.-01.09.2023
Compact localized states in magnonics, talk
G. Centała, and J. W. Kłos, talk
Abstract >>>

2D Quantum Materials for Spintronics, 2DQMS, Poznań, Poland, 29-31.01.2024
Compact localised states in magnonics
G. Centała, J. W. Kłos
Abstract >>>

Symposium on Spintronics and Quantum Information, Będlewo, Poland, 11-13.01, 2024
Spin wave localization induced by superconducting strip, talk
J. Kharlan, K. Sobucki, K. Szulc, S. Memarzadeh and J. W. Kłos
Abstract >>>

Symposium on Spintronics and Quantum Information, Będlewo, Poland, 11-13.01, 2024
The role of material parameters, external field and geometry on the arrangement of vortices in superconducting structures, poster
S. Memarzadeh and J. W. Kłos
Abstract >>>

Symposium on Spintronics and Quantum Information, Będlewo, Poland, 11-13.01, 2024
Simulation of unidirectional spin-waves generated by the Cherenkov effect in a ferromagnet/superconductor hybrid, poster
J. Hernández, M. Moalic and J. W. Kłos
Abstract >>>

IEEE International Magnetics Conference, INTERMAG 2024, Rio de Janeiro, Brazil, on May 5-10, 2024
Flat bands and compact localized states in magnonic crystals, talk
G. Centała, J. W. Kłos
Abstract >>>

IEEE International Magnetics Conference, INTERMAG 2024, Rio de Janeiro, Brazil, on May 5-10, 2024
Spin wave localization in ferromagnetic layer induced by superconducting nanostructure, talk
J. Kharlan, K. Sobucki, K. Szulc, S. Memarzadeh and J. W. Klos
Abstract >>>

1st Transnational Round Table on Magnonics, High-Frequency Spintronics, and Ultrafast Magnetism (TRTM’2024), Exeter, UK, 3-7.06.2024
Unconventional spin wave localization in magnonic nanostructures of long-range order, invted talk
J. W. Kłos, G. Centała, S. Mieszczak
Abstract >>>

1st Transnational Round Table on Magnonics, High-Frequency Spintronics, and Ultrafast Magnetism (TRTM’2024), Exeter, UK, 3-7.06.2024
Spin wave confinement in hybrid superconductor-ferromagnet nanostructure, poster
J. Kharlan, K. Sobucki,a K. Szulc, S. Memarzadeh and J. W. Klos
Abstract >>>

International Conference on Magnetism, 30.06 – 05.07.2024, Bologna, Italy
Spin wave localization in hybrid magnonic-superconducting naostructure, poster
J. Kharlan, K. Sobucki, K. Szulc, S. Memarzadeh, J. W. Klos
Abstract >>>

SolSkyMag, San Sebastian, Spain, 24 – 27.06, 2024
Creation of the skyrmions by the stray fields produced by superconducting ring, talk
Y. Kharlan, M. Zelent, K. Guslienko, V. Golub, J. W. Klos
Abstract >>>

Nanomaterials: Applications & Properties” (IEEE NAP 2024), Riga, Latvia, 8-13.09, 2024
Creation of the magnetic skyrmions by the stray fields produced by superconductor ring, talk
Abstract >>>

Thesis

Gauthier Philippe, master thesis