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

Mingyu Hu*, Ezio Iacocca, Mark A. Hoefer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

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.

Original languageEnglish
Article number1300105
Number of pages5
JournalIEEE Transactions on Magnetics
Volume58
Issue number2
Early online date3 May 2021
DOIs
Publication statusPublished - 1 Feb 2022

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