journal article·2021-07-01Open access

Field-free spin–orbit torque driven multi-state reversal in wedged Ta/MgO/CoFeB/MgO heterostructures

Dong Li, Baoshan Cui, Xiaobin Guo, Zhengyu Xiao, Wei Zhang, Xiaoxiong Jia, Jinyu Duan, Xu Liu, Jie Chen, Zhiyong Quan, Guoqiang Yu, Xiaohong Xu

APL Materials· Volume 9· Issue 7

Abstract

We report a current-induced four-state magnetization reversal under zero magnetic field in a wedged Ta/MgO/CoFeB/MgO heterostructure with a perpendicular magnetic anisotropy. Anomalous Hall effect and magneto-optical Kerr effect microscopy measurements were performed to demonstrate that the field-free multi-level reversal is jointly determined by the spin–orbit torque effective field that originates from the lack of the lateral inversion symmetry in the wedged stacking structure and the current-induced Oersted field. Moreover, the creation of robust intermediate Hall resistance states in the multi-state switching strongly depends on the current-induced Joule heating. Our results provide a route for the field-free multi-level state reversal, which is significant for fabricating the non-volatile and energy-efficient multi-level memories or artificial neuron devices.
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Research context

OpenAlex topics: Magnetic properties of thin films · ZnO doping and properties · Multiferroics and related materials

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Affiliations

Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education, Research Institute of Materials Science, Shanxi Normal University 1 , Linfen 041004, People’s Republic of China

Songshan Lake Materials Laboratory 2 , Dongguan, Guangdong 523808, People’s Republic of China

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences 3 , Beijing 100190, People’s Republic of China

School of Physics and Optoelectric Engineering, Guangdong University of Technology, Guangzhou Higher Education Mega Centre 4 , Guangzhou 510006, People’s Republic of China

School of Chemistry and Materials Science, Shanxi Normal University 5 , Linfen 041004, People’s Republic of China

Funding

Guangdong Basic and Applied basic Research Foundation · National Natural Science Foundation of China · China Postdoctoral Science Foundation · Youth Science Foundation of Shanxi Province · Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi · Program of Collaborative Innovation Center for Shanxi Advanced Permanent Materials and Technology · Natural Science Foundation of Shanxi Normal University

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