Spin-Injection-Generated Shock Waves and Solitons in a Ferromagnetic Thin Film

Hu, Mingyu, Iacocca, Ezio and Hoefer, Mark A. (2022) Spin-Injection-Generated Shock Waves and Solitons in a Ferromagnetic Thin Film. IEEE Transactions on Magnetics, 58 (2). pp. 1-5. ISSN 0018-9464

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Official URL: https://doi.org/10.1109/TMAG.2021.3077185


Unsteady nonlinear magnetization dynamics are studied in an easy-plane ferromagnetic channel subject to spin injection at one edge. The Landau-Lifshitz equation is known to support steady-state solutions, termed dissipative exchange flows (DEFs) or spin superfluids. In this work, by means of numerical simulations and theoretical analysis, we provide a full description of the injection-induced, large-amplitude, nonlinear magnetization dynamics up to the steady state. The dynamics prior to reaching steady state are driven by spin injection, a perpendicular applied magnetic field, the exchange interaction, and local demagnetizing fields. We show that the dynamics result in well-defined profiles in the form of rarefaction waves (RWs), dispersive shock waves (DSWs), and solitons. The realization of these coherent structures depends on the interplay between the spin injection strength and the applied magnetic field. A soliton at the injection boundary, signaling the onset of the magnetic 'supersonic' condition, rapidly develops and persists in the steady-state configuration of a contact soliton DEF. We also demonstrate the existence of sustained soliton-train dynamics in long time that can only arise in a nonzero applied magnetic field scenario. The dynamical evolution of spin-injection-induced magnetization dynamics presented here may help guide observations in long-distance spin transport experiments.

Item Type: Article
Additional Information: Funding information: This work was supported in part by the National Institute of Standards and Technology Professional Research Experience Program and in part by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-SC0018237.
Uncontrolled Keywords: Dispersive spin shock wave, ferromagnet, nonlinear dynamics, soliton, spin injection
Subjects: F300 Physics
H600 Electronic and Electrical Engineering
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 09 Feb 2022 14:09
Last Modified: 09 Feb 2022 14:15
URI: http://nrl.northumbria.ac.uk/id/eprint/48424

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