Interface-induced sign reversal of the anomalous Hall effect in magnetic topological insulator heterostructures

Fei Wang,Xuepeng Wang,Wei Liu,Di Xiao,Weiwei Zhao,Ling-Jie Zhou,Nitin Samarth,Cui-Zu Chang,Yi-Fan Zhao,Chaoxing Liu,Zhidong Zhang,Moses H W Chan,Haijun Zhang

doi:10.1038/s41467-020-20349-z

Abstract

The Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications.

Highlights

The Berry phase picture provides important insights into the electronic properties of condensed matter systems
Since the Berry phase encodes the adiabatic evolution of occupied eigen wave functions around the Fermi surface in the first Brillouin zone (BZ) of momentum space[4,5], it is important for understanding certain physical phenomena of quantum materials such as the intrinsic anomalous Hall (AH) effect[6]
The Berry curvature Ωð~kÞ of the occupied Bloch bands is equivalent to an effective magnetic field in momentum space; this can affect the motion of electrons and gives rise to the AH effect in ferromagnetic (FM) materials[6]

Summary

Introduction

The Berry phase picture provides important insights into the electronic properties of condensed matter systems. We carried out first-principles calculations and attributed this AH effect change to the interfaceinduced Berry curvature reconstruction, which occurs due to the band structure modulation of the magnetic TI layers induced by built-in electric fields.

Results

Conclusion