Room-Temperature Spin-Orbit Torque from Topological Surface States

Hao Wu, Peng Zhang, Peng Deng, Qianqian Lan, Quanjun Pan, Seyed Armin Razavi, Xiaoyu Che, Li Huang, Bingqian Dai, Kin Wong, Xiufeng Han, Kang L. Wang

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

Spin-momentum locked surface states in topological insulators (TIs) provide a promising route for achieving high spin-orbit torque (SOT) efficiency beyond the bulk spin-orbit coupling in heavy metals (HMs). However, in previous works, there is a huge discrepancy among the quantitative SOTs from TIs in various systems determined by different methods. Here, we systematically study the SOT in the TI(HM)/Ti/CoFeB/MgO systems by the same method, and make a conclusive assessment of SOT efficiency for TIs and HMs. Our results demonstrate that TIs show more than one order of magnitude higher SOT efficiency than HMs even at room temperature, at the same time the switching current density as low as 5.2×105 A cm-2 is achieved with (Bi1-xSbx)2Te3. Furthermore, we investigate the relationship between SOT efficiency and the position of Fermi level in (Bi1-xSbx)2Te3, where the SOT efficiency is significantly enhanced near the Dirac point, with the most insulating bulk and conducting surface states, indicating the dominating SOT contribution from topological surface states. This work unambiguously demonstrates the ultrahigh SOT efficiency from topological surface states.

Original languageEnglish
Article number207205
JournalPhysical review letters
Volume123
Issue number20
DOIs
Publication statusPublished - 2019 Nov 15

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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