Low-Power and Field-Free Perpendicular Magnetic Memory Driven by Topological Insulators.

Cui, Baoshan; Chen, Aitian; Zhang, Xu; Fang, Bin; Zeng, Zhaozhuo; Zhang, Peng; Zhang, Jing; He, Wenqing et al. · Adv Mater · 2023

basic_science · Level V

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Abstract

Giant spin-orbit torque (SOT) from topological insulators (TIs) has great potential for low-power SOT-driven magnetic random-access memory (SOT-MRAM). In this work, a functional 3-terminal SOT-MRAM device is demonstrated by integrating the TI [(BiSb)<sub>2</sub> Te<sub>3</sub> ] with perpendicular magnetic tunnel junctions (pMTJs), where the tunneling magnetoresistance is employed for the effective reading method. An ultralow switching current density of 1.5 × 10<sup>5</sup>  A cm<sup>-2</sup> is achieved in the TI-pMTJ device at room temperature, which is 1-2 orders of magnitude lower than that in conventional heavy-metals-based systems, due to the high SOT efficiency θ<sub>SH</sub> = 1.16 of (BiSb)<sub>2</sub> Te<sub>3</sub> . Furthermore, all-electrical field-free writing is realized by the synergistic effect of a small spin-transfer torque current during the SOT. The thermal stability factor (Δ = 66) shows the high retention time (>10 years) of the TI-pMTJ device. This work sheds light to the future low-power, high-density, and high-endurance/retention magnetic memory technology based on quantum materials.