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MA: Fachverband Magnetismus

MA 44: Non-Skyrmionic Magnetic Textures

MA 44.9: Vortrag

Donnerstag, 21. März 2024, 17:30–17:45, EB 301

Relativistic domain wall motion in ferrimagnets — •Pietro Diona — Scuola Normale Superiore di Pisa, Pisa, Italy — Italian Institute of Technology, Genova, Italy — ETH, Zurich, Switzerland

Domain walls in antiferromagnets are topological sine-Gordon solitons, characterized by relativistic kine- matics with the spin wave velocity setting a crucial limit for the operating speed of a magnetic racetrack memory. The relativistic kinematics of magnetic solitons was experimentally observed for the first time in crystalline ferrimagnets, but open questions on spin dynamics still remain. We aim to maximize the domain wall speed leveraging the tunability of amorphous alloys with rare-earth (RE) and transition-metal (TM) constituting two antiferromagnetic sublattices. By tuning RE concentration, it is possible to calibrate the anisotropy, the magnetization compensation point, and the net angular momentum compensation point, which are the keys to achieve high operating speeds in ferrimagnets. Here we extend the theoretical model describing the domain wall motion assisted by spin orbit torque and in-plane magnetic field [1] to the case of RE-TM systems, taking into account the phenomena of canting, domain wall width broadening and intrinsic pinning. It is proven that a domain wall in a RE-TM system can be described by a modified double sine-Gordon equation. The results are corroborated by magneto-optical Kerr effect (MOKE) measurements of the domain wall motion.

[1]P. Diona et al., IEEE Trans. on Electron Devices, 69(7), 3675 (2022).

Keywords: relativistic; domain wall; ferrimagnets; sine-Gordon; rare-earth-transition-metal