Interplay between exchange split Dirac and Rashba-type surface states in MnBi$_2$Te$_4$/BiTeI interface

TL;DR

This study uses ab initio calculations to explore how different interfaces in MnBi2Te4/BiTeI heterostructures affect electronic states, revealing potential for novel spintronic device design.

Contribution

It uncovers how interface types influence Dirac and Rashba surface states, offering insights into magnetic proximity effects in topological insulator heterostructures.

Findings

Te-Te interface causes slight exchange splitting of Dirac cone.

Te-I contact introduces four-band states with lifted degeneracies.

Magnetic proximity induces Hall response in transport measurements.

Abstract

Based on the ab initio calculations, we study the electronic structure of the BiTeI/MnBi2Te4 heterostructure interface composed of the anti-ferromagnetic topological insulator MnBi$_2$Te$_4$ and the polar semiconductor trilayer BiTeI. We found significant difference in electronic properties at different types of contact between substrate and the overlayer. While the case of Te-Te interface forms natural expansion of the substrate, when Dirac cone state locates mostly in the polar overlayer region and undergoes slight exchange splitting, Te-I contact is the source of four-band state contributed by the substrate Dirac cone and Rashba-type state of the polar trilayer. Owing to magnetic proximity, the pair of Kramers degeneracies for this state are lifted, what produces Hall response in transport regime. We believe, our findings provide new opportunities to construct novel type spintronic devices.