Evolution of the electronic structure of ultrathin MnBi2Te4 Films

TL;DR

This paper investigates how the electronic structure of ultrathin MnBi2Te4 films evolves with thickness and doping, revealing transitions from insulator to topological states and the emergence of Rashba-split bands, advancing quantum material engineering.

Contribution

It systematically studies the electronic structure evolution of MnBi2Te4 thin films, highlighting the effects of thickness and surface doping on topological and Rashba states, which was not previously understood.

Findings

Electronic structure transitions from insulator to topological states with increasing thickness.

Surface doping induces Rashba split bands that hybridize with topological surface states.

Insights into engineering quantum properties of MnBi2Te4 thin films for spintronics and quantum computing.

Abstract

Ultrathin films of intrinsic magnetic topological insulator MnBi2Te4 exhibit fascinating quantum properties such as quantum anomalous Hall effect and axion insulator state. In this work, we systematically investigate the evolution of the electronic structure of MnBi2Te4 thin films. With increasing film thickness, the electronic structure changes from an insulator-type with a large energy gap to one with in-gap topological surface states, which is, however, still drastically different from the bulk material. By surface doping of alkali-metal atoms, a Rashba split band gradually emerges and hybridizes with topological surface states, which not only reconciles the puzzling difference between the electronic structures of the bulk and thin film MnBi2Te4 but also provides an interesting platform to establish Rashba ferromagnet that is attractive for (quantum) anomalous Hall effect. Our results provide important insights into the understanding and engineering of the intriguing quantum properties of MnBi2Te4 thin films.