Chiral Symmetry Breaking for Deterministic Switching of Perpendicular Magnetization by Spin–Orbit Torque

• DOI: 10.1021/acs.nanolett.0c03972
• Publication Date: 2020-12-18T22:38:27Z
• Authors: 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
• Keywords: Condensed Matter - Materials Science; Condensed Matter - Mesoscale and Nanoscale Physics; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 02 engineering and technology; 0210 nano-technology

16 pages, 4 figures<br/>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.<br/>