Quantum Hall States Stabilized in Semi-magnetic Bilayers of Topological Insulators

TL;DR

This paper demonstrates the realization of robust quantum Hall states in magnetic topological insulator bilayers through tailored material design, revealing new topological transport phenomena.

Contribution

It introduces a novel heterostructure approach to stabilize quantum Hall states by combining magnetic and non-magnetic layers in topological insulators.

Findings

Quantum Hall states observed at filling factors 0 and +1.

Tailored heterostructures enable control over topological transport.

Cooperative or cancelling Hall responses from layers are demonstrated.

Abstract

By breaking the time-reversal-symmetry in three-dimensional topological insulators with introduction of spontaneous magnetization or application of magnetic field, the surface states become gapped, leading to quantum anomalous Hall effect or quantum Hall effect, when the chemical potential locates inside the gap. Further breaking of inversion symmetry is possible by employing magnetic topological insulator heterostructures that host nondegenerate top and bottom surface states. Here, we demonstrate the tailored-material approach for the realization of robust quantum Hall states in the bilayer system, in which the cooperative or cancelling combination of the anomalous and ordinary Hall responses from the respective magnetic and non-magnetic layers is exemplified. The appearance of quantum Hall states at filling factor 0 and +1 can be understood by the relationship of energy band diagrams for the two independent surface states. The designable heterostructures of magnetic topological insulator may explore a new arena for intriguing topological transport and functionality.