Approaching a Minimal Topological Electronic Structure in Antiferromagnetic Topological Insulator MnBi2Te4 via Surface Modification

TL;DR

This study demonstrates that surface potassium dosing can effectively modify the topological surface state in MnBi2Te4, removing trivial states and moving towards a minimal topological electronic structure in magnetic topological insulators.

Contribution

The paper shows that potassium surface modification can eliminate trivial surface states in MnBi2Te4, advancing the realization of a minimal topological electronic structure in magnetic topological insulators.

Findings

Potassium dosing removes trivial Rashba-type surface states.

Surface modification is driven by electrochemical reactions of K clusters.

Provides a clearer understanding of the band structure in MnBi2Te4.

Abstract

The topological electronic structure plays a central role in the non-trivial physical properties in topological quantum materials. A minimal, hydrogen-atom-like topological electronic structure is desired for researches. In this work, we demonstrate an effort towards the realization of such a system in the intrinsic magnetic topological insulator MnBi2Te4, by manipulating the topological surface state (TSS) via surface modification. Using high resolution laser- and synchrotron-based angle-resolved photoemission spectroscopy (ARPES), we found the TSS in MnBi2Te4 is heavily hybridized with a trivial Rashba-type surface state (RSS), which could be efficiently removed by the in situ surface potassium (K) dosing. By employing multiple experimental methods to characterize K dosed surface, we attribute such a modification to the electrochemical reactions of K clusters on the surface. Our work not only gives a clear band assignment in MnBi2Te4, but also provides possible new routes in accentuating the topological behavior in the magnetic topological quantum materials.