Quantum anomalous Hall effect driven by magnetic proximity coupling in all-telluride based heterostructure

Abstract

The quantum anomalous Hall effect (QAHE) is an exotic quantum phenomenon originating from dissipation-less chiral channels at the sample edge. While the QAHE has been observed in magnetically doped topological insulators (TIs), exploiting magnetic proximity effect on the TI surface from adjacent ferromagnet layers may provide an alternative approach to the QAHE by opening an exchange gap with less disorder than that in the doped system. Nevertheless, the engineering of a favorable heterointerface that realizes the QAHE based on the magnetic proximity effect remains to be achieved. Here, we report on the observation of the QAHE in a proximity coupled system of nonmagnetic TI and ferromagnetic insulator (FMI). We have designed sandwich heterostructures of (Zn,Cr)Te/(Bi,Sb)2Te3/(Zn,Cr)Te that fulfills two prerequisites for the emergence of the QAHE; the formation of a sizable exchange gap at the TI surface state and the tuning of the Fermi energy into the exchange gap. The efficient proximity coupling in the all-telluride based heterostructure as demonstrated here will enable a realistic design of versatile tailor-made topological materials coupled with ferromagnetism, ferroelectricity, superconductivity, and so on.

Current-induced switching of proximity-induced ferromagnetic surface states in a topological insulator

“…pin-polarized surface electronic states of three-dimensional topological insulators (TIs) offer novel physical properties, being potentially applicable to future low-powerconsumption electronics/spintronics and topological quantum computation 1 . One of the representative features is the emergence of anomalous Hall conductance in the gapped surface state when magnetization perpendicular to the surface is induced by the incorporation of magnetic elements or proximity coupling with a ferromagnetic (FM) layer on the TI [2][3][4][5][6][7][8] . This magnetic TI exhibits exotic magnetic insulating phases, such as a quantum anomalous Hall (QAH) insulator and an axion insulator.…”

Recent progress in the research of quantum anomalous <?A3B2 ACK?>Hall effect

“…Copyright © 2017 John Wiley and Sons. 三明治结构的结构示意图(g)、霍尔电阻和纵向电阻随磁场(h)及温度(i)的变化曲线 [32] . Copyright © 2019 AIP Publishing Figure 3 The structural schematic diagram for QAH system.…”

“…(a) Penta-layer structure which has the heavily magnetically doped (HMD) layer as subsurface layer; temperature dependence of R yx (b) and R xx (c) [24] , Copyright © 2015 AIP Publishing; (d) magnetic co-doped TI for QAH; (e) temperature and (f) back gate voltage dependence of ρ yx (0) and ρ xx (0) [26] , Copyright © 2017 John Wiley and Sons. The red arrow indicates the direction of magnetic moment; (g) sandwich heterostructure for QAH; (h) magnetic field and (i) temperature dependence of R yx and R xx [32] , [37,38] ; Copyright © 2015 AIP Publishing. (c) 磁化反转过程中 的磁畴模型示意图 [37] .…”

“…本研究组 [26] [33] . 最 近, 日本Tokura研究组 [32] 制备了(Zn,Cr)/(Bi,Sb) [24] . 而近期备受关注的层状磁性材 料 [34,35] Figure 2 Magnetic disorder in magnetically doped TIs.…”

Termination switching of antiferromagnetic proximity effect in topological insulator

“…Since the realization of the quantum anomalous Hall effect (QAHE) in magnetic topological insulators (TIs) (1)(2)(3)(4), there has been enormous interest in bringing quantum transport effects to room temperature. One of the most promising approaches to achieve room temperature quantum transport has been the use of magnetic proximity effects (MPEs) to induce magnetic order in a TI by coupling it to an adjacent magnetically ordered material (5)(6)(7)(8)(9)(10)(11). The coupling between the TI and the magnetically ordered material may stabilize high-temperature magnetic order in TI through the exchange interaction while preserving the topologically protected surface states.…”