# Topological surface states above the Fermi energy in $\textrm{Hf}_{2}\textrm{Te}_2\textrm{P}$

## TL;DR

This study experimentally investigates the band structure of Hf2Te2P, revealing topological surface states above the Fermi level through advanced spectroscopy techniques, confirming theoretical predictions and highlighting potential for improved surface conductance.

## Contribution

First experimental observation of topological surface states above the Fermi level in Hf2Te2P using combined spectroscopic methods.

## Key findings

- Detection of multiple Dirac-like surface states
- Experimental confirmation of a topological state at 460 meV
- Band inversion involving Hf-d and Te-p orbitals

## Abstract

We report a detailed experimental study of the band structure of the recently discovered topological material $\textrm{Hf}_{2}\textrm{Te}_2\textrm{P}$. Using the combination of scanning tunneling spectroscopy and angle-resolved photo-emission spectroscopy with surface K-doping, we probe the band structure of $\textrm{Hf}_{2}\textrm{Te}_2\textrm{P}$ with energy and momentum resolution above the Fermi level. Our experiments show the presence of multiple surface states with a linear Dirac-like dispersion, consistent with the predictions from previously reported band structure calculations. In particular, scanning tunneling spectroscopy measurements provide the first experimental evidence for the strong topological surface state predicted at 460 meV, which stems from the band inversion between Hf-d and Te-p orbitals. This band inversion comprised of more localized d-states could result in a better surface-to-bulk conductance ratio relative to more traditional topological insulators.