# 3D nature of ZrTe$_5$ band structure measured by high-momentum-resolution photoemission spectroscopy

## TL;DR

This study uses high-resolution photoemission spectroscopy to investigate the 3D band structure of ZrTe$_5$, revealing an intrinsic gap and clarifying its topological classification as a weak topological insulator.

## Contribution

First high-momentum-resolution photoemission measurements of ZrTe$_5$ near the $b3$ point, establishing its intrinsic band gap and 3D topological nature.

## Key findings

- Measured the band gap as 18-29 meV.
- Observed photon-energy-dependent behavior due to final-state effects.
- Concluded ZrTe$_5$ is a 3D weak topological insulator.

## Abstract

We have performed a systematic high-momentum-resolution photoemission study on ZrTe$_5$ using $6$ eV photon energy. We have measured the band structure near the $\Gamma$ point, and quantified the gap between the conduction and valence band as $18 \leq \Delta \leq 29$ meV. We have also observed photon-energy-dependent behavior attributed to final-state effects and the 3D nature of the material's band structure. Our interpretation indicates the gap is intrinsic and reconciles discrepancies on the existence of a topological surface state reported by different studies. The existence of a gap suggests that ZrTe$_5$ is not a 3D strong topological insulator nor a 3D Dirac semimetal. Therefore, our experiment is consistent with ZrTe$_5$ being a 3D weak topological insulator.