SPICE Workshop on Spin textures: Magnetism meets Plasmonics, July 23rd - 25th 2024
Alexandra Kalashnikova
Efficient generation, propagation, control, and detection of spin waves is essential for development of magnonic components for conventional and neuromorphic computing [1]. Although spin wave wavelengths reach nanometers, while their frequencies reach terahertz, working with waves possessing short wavelength and high frequencies is a challenging task in magnonics. Promising approach to this issue is to exploit femtomagnetic phenomena – ultrafast laser-induced changes of magnetic parameters [2] in combination with strong localization of laser pulses using plasmonic and photonic structures.
In this talk, we first discuss laser-induced generation of magnetostatic waves - spin waves near the centre of the Brillouin zone in anisotropic ferromagnetic films [3-5], which are already used in magnonics. While we use conventional approach to focusing laser pulses, our findings can be readily combined with plasmonics to reduce spin wavelength down to the exchange wave range. Based on experimental findings and micromagnetic simulations, we suggest tuneable laser-driven sources of magnetostatic wavepackets using spin textures in a vicinity of a domain wall [6] or waveguide edges [7].
We further tackle a problem of reaching ultimate exchange waves – those at the edge of the Brillouin zone, that cannot be realized even by focusing of a laser pulse below diffraction limit. We show how ultrafast perturbation of the exchange interaction drives coupled magnons pairs in the whole Brillouin zone – two-magnon modes, derive selection rules for their excitation and detection [8,9], and outline an approach to selective excitation of two-magnon modes with different wavevectors.
Author is grateful to the members of Ferroics Physics Laboratory at Ioffe Institute as well as to J. H. Mentink, A. V. Kimel, A. W. Rushforth for fruitful collaboration. The work is partially supported by RSF grant no. 23-12-00251 (https://rscf.ru/project/23-12-00251/).
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[4] Ia. A. Filatov et al., Appl. Phys. Lett. 120, 112404 (2022).
[5] N.E. Khokhlov et al., J. Magn. Magn. Mater. 589, 171514 (2024).
[6] N. E. Khokhlov et al., J. Magn. Magn. Mater. 534, 168018 (2021).
[7] P. I. Gerevenkov et al., Phys. Rev. Appl. 19, 024062 (2023).
[8] A. E. Fedianin et al., Phys, Rev Appl. 107, 144430 (2023).
[9] F. Formisano et al., APL Mater. 12, 011105 (2024).