Observation of Giant Band Splitting in Altermagnetic MnTe

TL;DR

This study provides direct experimental evidence of large, anisotropic band-splitting in altermagnetic MnTe using ARPES, revealing significant potential for novel physical properties related to altermagnetic spin-splitting.

Contribution

First direct observation of giant, anisotropic altermagnetic band-splitting in MnTe through combined ARPES and first-principles calculations.

Findings

Band-splitting reaches 0.8 eV at non-high-symmetry points.

Splitting is associated with time-reversal-symmetry breaking.

Splitting magnitude exceeds spin-orbit gap of 0.3 eV.

Abstract

We performed angle-resolved photoemission spectroscopy (ARPES) on hexagonal MnTe, a candidate for an altermagnet with a high critical temperature (TN=307 K). By utilizing photon-energy-tunable ARPES in combination with first-principles calculations, we found that the band structure in the antiferromagnetic phase exhibits a strongly anisotropic band-splitting associated with the time-reversal-symmetry breaking, providing the first direct experimental evidence for the altermagnetic band-splitting. The magnitude of the splitting reaches 0.8 eV at non-high-symmetry momentum points, which is much larger than the spin-orbit gap of ~0.3 eV along the GK high-symmetry cut. The present result paves the pathway toward realizing exotic physical properties associated with the altermagnetic spin-splitting.