Insulator-to-conductor transition driven by the Rashba\u2013Zeeman effect

Lingling Tao,Evgeny Y Tsymbal

doi:10.1038/s41524-020-00441-0

Abstract

The Rashba effect has recently attracted great attention owing to emerging physical properties associated with it. The interplay between the Rashba effect and the Zeeman effect, being produced by the exchange field, is expected to broaden the range of these properties and even result in novel phenomena. Here we predict an insulator-to-conductor transition driven by the Rashba–Zeeman effect. We first illustrate this effect using a general Hamiltonian model and show that the insulator-to-conductor transition can be triggered under certain Rashba and exchange-field strengths. Then, we exemplify this phenomenon by considering an Ag2Te/Cr2O3 heterostructure, where the electronic structure of the Ag2Te monolayer is affected across the interface by the proximity effect of the Cr2O3 antiferromagnetic layer with well-defined surface magnetization. Based on first-principles calculations, we predict that such a system can be driven into either insulating or conducting phase, depending on the surface magnetization orientation of the Cr2O3 layer. Our results enrich the Rashba–Zeeman physics and provide useful guidelines for the realization of the insulator-to-conductor transition, which may be interesting for experimental verification.

Highlights

The Rashba effect is a momentum-dependent spin splitting of the energy bands driven by spin-orbit coupling (SOC)[1]
Owing to broken inversion symmetry, an Ag2Te monolayer exhibits a sizable Rashba band splitting, while the Cr2O3 substrate has a robust surface magnetization coupled to the AFM order parameter and provides an exchange field affecting the electronic structure of the Ag2Te through the proximity effect
Based on density-functional theory (DFT) calculations, we demonstrate that such a system can be driven into either insulating or conducting phase, depending on the boundary magnetization orientation of the Cr2O3 layer

Summary

Introduction

The Rashba effect is a momentum-dependent spin splitting of the energy bands driven by spin-orbit coupling (SOC)[1]. The band structure of the 2D material can be controlled by the exchange field orientation, and under certain Rashba and exchange field strengths exhibits an insulator-to-conductor transition. Owing to broken inversion symmetry, an Ag2Te monolayer exhibits a sizable Rashba band splitting, while the Cr2O3 substrate has a robust surface magnetization coupled to the AFM order parameter and provides an exchange field affecting the electronic structure of the Ag2Te through the proximity effect.

Results

Conclusion