Evidence for a Strong Topological Insulator Phase in $\mathrm{ZrTe_5}$

TL;DR

This study provides comprehensive experimental and theoretical evidence that ZrTe_5 is a strong topological insulator, characterized by surface and bulk states confirmed through spectroscopy and ab initio calculations.

Contribution

The paper demonstrates that ZrTe_5 is a strong topological insulator through combined spectroscopic, structural, and theoretical analyses, clarifying its electronic phase.

Findings

Identification of surface and bulk states at the valence band top

Agreement of band dispersion with ab initio STI calculations

Confirmation of metallic surface character via tunneling spectroscopy

Abstract

The complex electronic properties of $\mathrm{ZrTe_5}$ have recently stimulated in-depth investigations that assigned this material to either a topological insulator or a 3D Dirac semimetal phase. Here we report a comprehensive experimental and theoretical study of both electronic and structural properties of $\mathrm{ZrTe_5}$, revealing that the bulk material is a strong topological insulator (STI). By means of angle-resolved photoelectron spectroscopy, we identify at the top of the valence band both a surface and a bulk state. The dispersion of these bands is well captured by ab initio calculations for the STI case, for the specific interlayer distance measured in our x-ray diffraction study. Furthermore, these findings are supported by scanning tunneling spectroscopy revealing the metallic character of the sample surface, thus confirming the strong topological nature of $\mathrm{ZrTe_5}$.