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

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.

21 page, 9 figures

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• Skyrmion Hall Effect Revealed by Direct Time-Resolved X-Ray Microscopy
• Creep and flow regimes of magnetic domain wall motion in ultrathin Pt/Co/Pt films with perpendicular anisotropy
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Cited by in corpus (6)

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• Current-induced dynamics of skyrmion tubes in synthetic antiferromagnetic multilayers
• Spin-wave-driven skyrmion dynamics in ferrimagnets: Effect of net angular momentum
• Evidence of extreme domain wall speeds under ultrafast optical excitation
• Survey of 360${}^{\circ }$ domain walls in magnetic heterostructures: topology, chirality and current-driven dynamics
• Magnetic Bloch-point hopping in multilayer skyrmions and associated emergent electromagnetic signatures