Cai Jiaqi, Ovchinnikov Dmitry, Fei Zaiyao, He Minhao, Song Tiancheng, Lin Zhong, Wang Chong, Cobden David, Chu Jiun-Haw, Cui Yong-Tao, Chang Cui-Zu, Xiao Di, Yan Jiaqiang, Xu Xiaodong
Department of Physics, University of Washington, Seattle, WA, 98195, USA.
Department of Materials Science and Engineering, University of Washington, Seattle, WA, 98195, USA.
Nat Commun. 2022 Mar 29;13(1):1668. doi: 10.1038/s41467-022-29259-8.
The interplay between band topology and magnetism can give rise to exotic states of matter. For example, magnetically doped topological insulators can realize a Chern insulator that exhibits quantized Hall resistance at zero magnetic field. While prior works have focused on ferromagnetic systems, little is known about band topology and its manipulation in antiferromagnets. Here, we report that MnBiTe is a rare platform for realizing a canted-antiferromagnetic (cAFM) Chern insulator with electrical control. We show that the Chern insulator state with Chern number C = 1 appears as the AFM to canted-AFM phase transition happens. The Chern insulator state is further confirmed by observing the unusual transition of the C = 1 state in the cAFM phase to the C = 2 orbital quantum Hall states in the magnetic field induced ferromagnetic phase. Near the cAFM-AFM phase boundary, we show that the dissipationless chiral edge transport can be toggled on and off by applying an electric field alone. We attribute this switching effect to the electrical field tuning of the exchange gap alignment between the top and bottom surfaces. Our work paves the way for future studies on topological cAFM spintronics and facilitates the development of proof-of-concept Chern insulator devices.
能带拓扑与磁性之间的相互作用能够产生奇异的物质状态。例如，磁性掺杂的拓扑绝缘体可以实现一种在零磁场下表现出量子化霍尔电阻的陈绝缘体。尽管先前的研究主要集中在铁磁系统上，但对于反铁磁体中的能带拓扑及其调控却知之甚少。在此，我们报道MnBiTe是一个通过电控制实现倾斜反铁磁（cAFM）陈绝缘体的罕见平台。我们表明，当反铁磁向倾斜反铁磁相变发生时，陈数C = 1的陈绝缘体状态出现。通过观察cAFM相中C = 1状态到磁场诱导铁磁相中C = 2轨道量子霍尔状态的异常转变，进一步证实了陈绝缘体状态。在cAFM - 反铁磁相边界附近，我们表明仅通过施加电场就可以开启和关闭无耗散的手性边缘输运。我们将这种开关效应归因于上下表面之间交换能隙对齐的电场调谐。我们的工作为未来拓扑cAFM自旋电子学的研究铺平了道路，并促进了概念验证陈绝缘体器件的发展。
