Observation of non-trivial topological electronic structure of orthorhombic SnSe

TL;DR

This study combines experimental and theoretical methods to reveal that orthorhombic SnSe is a strong topological insulator, uncovering its non-trivial electronic structure and topological surface states, which influence its transport properties.

Contribution

It is the first comprehensive investigation demonstrating the topological insulator nature of orthorhombic SnSe through combined spectroscopy and ab-initio calculations.

Findings

SnSe exhibits a continuous gap in valence bands due to band inversion.

Identification of topological surface states on the (001) surface.

Proposed topological phase diagram for SnSe1-xTex.

Abstract

Topological electronic structures are key to the topological classification of quantum materials and play an important role in their physical properties and applications. Recently, SnSe has attracted great research interests due to its superior thermoelectric performance. However, it's topological nature has long been ignored. In this work, by combining synchrotron-based angle-resolved photoemission spectroscopy and ab-initio calculations, we systematically investigated the topological electronic structure of orthorhombic SnSe. By identifying the continuous gap in the valence bands due to the band inversion and the topological surface states on its (001) surface, we establish SnSe as a strong topological insulator. Furthermore, we studied the evolution of the topological electronic structure and propose the topological phase diagram in SnSe1-xTex. Our work reveals the topological non-trivial nature of SnSe and provides new understandings of its intriguing transport properties.