Reconstructing the wavefunction of magnetic topological insulators MnBi2Te4 and MnBi4Te7 using spin-resolved photoemission

TL;DR

This paper uses advanced spin-resolved photoemission to directly image and model the surface states of magnetic topological insulators MnBi2Te4 and MnBi4Te7, revealing their complex spin-orbital textures and a new gap reduction mechanism.

Contribution

It introduces a direct imaging and modeling approach for surface states in magnetic topological insulators, clarifying their spin-orbital structure and uncovering a novel gap reduction mechanism.

Findings

Mapped spin-polarization and orbital character of surface states

Established the single-band nature of prominent states

Discovered a new mechanism for reducing the magnetic gap

Abstract

Despite their importance for exotic quantum effects, the surface electronic structure of magnetic topological insulators MnBi2Te4 and MnBi4Te7 remains poorly understood. Using high-efficiency spin- and angle-resolved photoemission spectroscopy, we directly image the spin-polarization and orbital character of the surface states in both compounds and map our observations onto a model wavefunction to describe the complex spin-orbital texture, which solidifies our understanding of the surface band structure by establishing the single-band nature of the most prominent states. Most importantly, our analysis reveals a new mechanism for reducing the magnetic gap of the topological surface states based on the orbital composition of the wavefunction.