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arXiv · 1910.07168

Walker breakdown with a twist: Dynamics of multilayer domain walls and skyrmions driven by spin-orbit torque

Ivan Lemesh·Geoffrey S. D. Beach
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Abstract

Current-induced dynamics of twisted domain walls and skyrmions in ferromagnetic perpendicularly magnetized multilayers is studied through three-dimensional micromagnetic simulations and analytical modeling. It is shown that such systems generally exhibit a Walker breakdown-like phenomenon in the presence of current-induced damping-like spin-orbit torque. Above a critical current threshold, corresponding to typical velocities of the order tens of m/s, domain walls in some layers start to precess with frequencies in the gigahertz regime, which leads to oscillatory motion and a significant drop in mobility. This phenomenon originates from complex stray field interactions and occurs for a wide range of multilayer materials and structures that include at least three ferromagnetic layers and finite Dzyaloshinskii-Moriya interaction. An analytical model is developed to describe the precessional dynamics in multilayers with surface-volume stray field interactions, yielding qualitative agreement with micromagnetic simulations.

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Ivan Lemesh, Geoffrey S. D. Beach. 2019-10-16. Walker breakdown with a twist: Dynamics of multilayer domain walls and skyrmions driven by spin-orbit torque. https://doi.org/10.1103/physrevapplied.12.044031

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