R&D: L-Shape Electrode Design for High-Density Spin-Orbit Torque MRAM With Perpendicular Shape Anisotropy

Journal of Physics D: Applied Physics has published an article written by Kequn Chi, State Key Laboratory of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, People’s Republic of China, Yinuo Shi, Zhou Li, Wenbiao Zhang, Yun Xing, Xiang Feng, Key Laboratory of Spintronics Materials, Devices and Systems of Zhejiang Province, Hangzhou 311300, People’s Republic of China, Yungui Ma, State Key Laboratory of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, People’s Republic of China, Hao Meng, and Bo Liu, Key Laboratory of Spintronics Materials, Devices and Systems of Zhejiang Province, Hangzhou 311300, People’s Republic of China.

Abstract: “Magnetic tunneling junction with strong perpendicular shape anisotropy attracts more attention for high density magnetic random access memory. As thermal stability increases, the power consumption also increases. To solve this problem, devices are made driven by spin-orbit torque instead of spin-transfer torque. However, the assisting field needed for deterministic switching is a main obstacle for spin-orbit torque devices. In this work, we demonstrate an L-shape electrode structure attached to the magnetic recording layer to induce a composite spin-orbit torque, achieving high-speed and field-free magnetization switching. Meanwhile, the comparative study between L-shape and sidewall electrode structure demonstrates that the L-shape structure leads to fast and low-power switching. Finally, the switching characteristic at various current density and spin Hall angle is studied and it turns out that to achieve high-speed reversal, the current density and the spin Hall angle need to be optimized, which might be attributed to strong in-plane effective field component disturbance. The novel L-shape structure is feasible for high-speed, low-power and deterministic switching and has great potentials in spintronic applications.“