Topological band inversion in HgTe(001): surface and bulk signatures from photoemission

TL;DR

This study combines experimental photoemission and theoretical calculations to reveal the detailed electronic structure and band inversion in strained HgTe(001), confirming its topological insulator properties and the role of Hg 5d states.

Contribution

It provides a comprehensive experimental and theoretical analysis of HgTe's electronic structure, clarifying the band inversion and surface-bulk signatures in the topological regime.

Findings

Direct imaging of band inversion in HgTe

Agreement between experiment and density functional theory

Identification of surface and bulk electronic contributions

Abstract

HgTe is a versatile topological material and has enabled the realization of a variety of topological states, including two- and three-dimensional (3D) topological insulators and topological semimetals. Nevertheless, a quantitative understanding of its electronic structure remains challenging, in particular due to coupling of the Te 5p-derived valence electrons to Hg 5d core states at shallow binding energy. We present a joint experimental and theoretical study of the electronic structure in strained HgTe(001) films in the 3D topological-insulator regime, based on angle-resolved photoelectron spectroscopy and density functional theory. The results establish detailed agreement in terms of (i) electronic band dispersions and orbital symmetries, (ii) surface and bulk contributions to the electronic structure, and (iii) the importance of Hg 5d states in the valence-band formation. Supported by theory, our experiments directly image the paradigmatic band inversion in HgTe, underlying its non-trivial band topology.