Giant Hall Switching by Surface-State-Mediated Spin-Orbit Torque in a Hard Ferromagnetic Topological Insulator

• Published in: arXiv.org 2024-08
• Main Authors: Tai, Lixuan, He, Haoran, Su Kong Chong, Zhang, Huairuo, Huang, Hanshen, Qiu, Gang, Li, Yaochen, Hung-Yu, Yang, Yang, Ting-Hsun, Dong, Xiang, Ren, Yuxing, Dai, Bingqian, Qu, Tao, Shu, Qingyuan, Pan, Quanjun, Zhang, Peng, Xue, Fei, Li, Jie, Davydov, Albert V, Wang, Kang L
• Format: Article
• Language: English
• Subjects: Antimony; Bismuth; Coercivity; Ferromagnetism; Magnetization; Memory devices; Switching; Topological insulators; Torque
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2306.05603

Topological insulators (TI) and magnetic topological insulators (MTI) can apply highly efficient spin-orbit torque (SOT) and manipulate the magnetization with their unique topological surface states with ultra-high efficiency. Here, we demonstrate efficient SOT switching of a hard MTI, V-doped (Bi,Sb)2Te3 (VBST) with a large coercive field that can prevent the influence of an external magnetic field. A giant switched anomalous Hall resistance of 9.2 \(k\Omega\) is realized, among the largest of all SOT systems, which makes the Hall channel a good readout and eliminates the need to fabricate complicated magnetic tunnel junction (MTJ) structures. The SOT switching current density can be reduced to \(2.8\times10^5 A/cm^2\). Moreover, as the Fermi level is moved away from the Dirac point by both gate and composition tuning, VBST exhibits a transition from edge-state-mediated to surface-state-mediated transport, thus enhancing the SOT effective field to \(1.56\pm 0.12 T/ (10^6 A/cm^2)\) and the interfacial charge-to-spin conversion efficiency to \(3.9\pm 0.3 nm^{-1}\). The findings establish VBST as an extraordinary candidate for energy-efficient magnetic memory devices.