Symmetry Enforced Chiral Hinge States and Surface Quantum Anomalous Hall Effect in Magnetic Axion Insulator $\text{Bi}_{2-x}\text{Sm}_x\text{Se}_3$

TL;DR

This paper proposes a universal mechanism for generating chiral hinge states in magnetic axion insulators, leading to surface quantum anomalous Hall effects that can be manipulated via crystalline symmetry and magnetization, demonstrated in Sm-doped Bi2Se3.

Contribution

It introduces a new universal mechanism for chiral hinge states in magnetic axion insulators and proposes a realistic material system to realize and control surface QAHE.

Findings

Chiral hinge states can be generated in ferromagnetic axion insulators.

Surface quantum anomalous Hall effect can be manipulated via symmetry and magnetization.

Sm-doped Bi2Se3 is a promising candidate for experimental realization.

Abstract

A universal mechanism to generate chiral hinge states in the ferromagnetic axion insulator phase is proposed, which leads to an exotic transport phenomena, the quantum anomalous Hall effect (QAHE) on some particular surfaces determined by both the crystalline symmetry and the magnetization direction. A realistic material system Sm doped $\text{Bi}_2\text{Se}_3$ is then proposed to realize such exotic hinge states by combing the first principle calculations and the Green's function techniques. A physically accessible way to manipulate the surface QAHE is also proposed, which makes it very different from the QAHE in ordinary 2D systems.