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

TL;DR

This paper demonstrates the realization of the quantum anomalous Hall effect in a heterostructure of non-magnetic topological insulator and ferromagnetic insulator via magnetic proximity coupling, offering a less disordered alternative to magnetic doping.

Contribution

It reports the first observation of QAHE driven by magnetic proximity effect in all-telluride based heterostructures, enabling new design strategies for topological materials.

Findings

QAHE observed in (Zn,Cr)Te/(Bi,Sb)2Te3/(Zn,Cr)Te heterostructures

Sizable exchange gap at the TI surface state achieved

Fermi energy tuned into the exchange gap

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 non-magnetic 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.