Chiral symmetry breaking for deterministic switching of perpendicular magnetization by spin-orbit torque

Hao Wu, John Nance, Seyed Armin Razavi, David Lujan, Bingqian Dai, Yuxiang Liu, Haoran He, Baoshan Cui, Di Wu, Kin Wong, Kemal Sobotkiewich, Xiaoqin Li, Gregory P. Carman, Kang L. Wang

Published 2020-04-28Version 1

Symmetry breaking is a characteristic to determine which branch of a bifurcation system follows upon crossing a critical point. Specifically, in spin-orbit torque (SOT) devices, a fundamental question arises: how to break the symmetry of the perpendicular magnetic moment by the in-plane spin polarization? Here, we show that the chiral symmetry breaking by the DMI can induce the deterministic SOT switching of the perpendicular magnetization. By introducing a gradient of saturation magnetization or magnetic anisotropy, non-collinear spin textures are formed by the gradient of effective SOT strength, and thus the chiral symmetry of the SOT-induced spin textures is broken by the DMI, resulting in the deterministic magnetization switching. We introduce a strategy to induce an out-of-plane (z) gradient of magnetic properties, as a practical solution for the wafer-scale manufacture of SOT devices.