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arXiv · 2102.07909

Dynamic symmetry breaking in chiral magnetic systems

Jeffrey A. Brock·Michael D. Kitcher·Pierre Vallobra·Rajasekhar Medapalli·Maxwell P. Li·Marc De Graef·Stéphane Mangin·Vincent Sokalski·Eric E. Fullerton
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Abstract

The Dzyaloshinskii-Moriya interaction (DMI) in magnetic systems stabilizes spin textures with preferred chirality, applicable to next-generation memory and computing architectures. In perpendicularly magnetized heavy-metal/ferromagnet films, the interfacial DMI originating from structural inversion asymmetry and strong spin-orbit coupling favors chiral N\'eel-type domain walls (DWs) whose energetics and mobility remain at issue. Here, we characterize a new effect in which domains expand unidirectionally in response to a combination of out-of-plane and in-plane magnetic fields, with the growth direction controlled by the in-plane field strength. These growth directionalities and symmetries with applied fields cannot be understood from static treatments alone. We theoretically demonstrate that perpendicular field torques stabilize steady-state magnetization profiles highly asymmetric in elastic energy, resulting in a dynamic symmetry breaking consistent with the experimental findings. This phenomenon sheds light on the mechanisms governing the dynamics of N\'eel-type DWs and expands the utility of field-driven DW motion to probe and control chiral DWs.

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Jeffrey A. Brock, Michael D. Kitcher, Pierre Vallobra, Rajasekhar Medapalli, Maxwell P. Li, Marc De Graef, Stéphane Mangin, Vincent Sokalski, Eric E. Fullerton. 2021-02-16. Dynamic symmetry breaking in chiral magnetic systems. https://doi.org/10.1002/adma.202101524

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