Ultra-efficient spin-orbit torque induced magnetic switching in W/CoFeB/MgO structures

Xiaoxuan Zhao; Xueying Zhang; Huaiwen Yang; Wenlong Cai; Yinglin Zhao; Zhaohao Wang; Weisheng Zhao

doi:10.1088/1361-6528/ab1c02

Ultra-efficient spin-orbit torque induced magnetic switching in W/CoFeB/MgO structures

Nanotechnology. 2019 Aug 16;30(33):335707. doi: 10.1088/1361-6528/ab1c02. Epub 2019 Apr 24.

Authors

Xiaoxuan Zhao¹, Xueying Zhang, Huaiwen Yang, Wenlong Cai, Yinglin Zhao, Zhaohao Wang, Weisheng Zhao

Affiliation

¹ Fert Beijing Institute, BDBC, School of Microelectronics, Beihang University, Beijing, People's Republic of China. Centre de Nanosciences et de Nanotechnologies, Université Paris-Sud, Université Paris-Saclay, 91120 Palaiseau, France.

PMID: 31018193
DOI: 10.1088/1361-6528/ab1c02

Abstract

Spin-orbit torque (SOT) induced magnetic switching in heavy metal/ferromagnet structures with perpendicular magnetic anisotropy (PMA) is promising for energy efficient spintronic devices. Here, we studied the SOT induced magnetic switching in perpendicular W/Co₂₀Fe₆₀B₂₀/MgO structures. We demonstrated the critical current density for the SOT induced switching is as low as 1.15 × 10⁶ A cm^-2 in the presence of an in-plane magnetic field, which is very energy efficient in terms of magnetic switching. We attribute this ultra-efficient magnetic switching to the high spin Hall angle of the W layer and the ultra-low domain wall pinning field of the CoFeB. The SOT induced switching procedure was directly observed by a high-resolution Kerr microscopy. Furthermore, the weak Dzyaloshinsky-Moriya interactions are shown to be favorable for switching. Our experiments physically explained the ultra-efficient SOT induced magnetic switching in W/CoFeB/MgO structures, and direct observation of the switching procedure can improve the comprehensive understanding of this dynamic process and further promote the study of SOT based memory devices.