Semiconducting Electronic Structure of the Ferromagnetic Spinel $\mathbf{Hg}\mathbf{Cr}_2\mathbf{Se}_4$ Revealed by Soft-X-Ray Angle-Resolved Photoemission Spectroscopy

TL;DR

This study combines SX-ARPES experiments and first-principles calculations to reveal that the ferromagnetic spinel HgCr2Se4 is a semiconductor, contradicting prior predictions of it being a Weyl semimetal.

Contribution

The paper provides the first direct experimental evidence and theoretical confirmation that HgCr2Se4 is a ferromagnetic semiconductor, challenging previous theoretical predictions.

Findings

SX-ARPES shows a semiconducting state in ferromagnetic HgCr2Se4.

Density functional theory calculations reproduce the observed band gap.

The material is not a Weyl semimetal as previously predicted.

Abstract

We study the electronic structure of the ferromagnetic spinel $\mathrm{Hg}\mathrm{Cr}_2\mathrm{Se}_4$ by soft-x-ray angle-resolved photoemission spectroscopy (SX-ARPES) and first-principles calculations. While a theoretical study has predicted that this material is a magnetic Weyl semimetal, SX-ARPES measurements give direct evidence for a semiconducting state in the ferromagnetic phase. Band calculations based on the density functional theory with hybrid functionals reproduce the experimentally determined band gap value, and the calculated band dispersion matches well with ARPES experiments. We conclude that the theoretical prediction of a Weyl semimetal state in $\mathrm{Hg}\mathrm{Cr}_2\mathrm{Se}_4$ underestimates the band gap, and this material is a ferromagnetic semiconductor.