Observation of a giant band splitting in altermagnetic MnTe

Abstract

This paper reports angle-resolved photoemission spectroscopy and first-principles band calculations for MnTe, a candidate for an altermagnet that is now emerging as a new type of magnet, distinct from conventional ferromagnets and antiferromagnets. The authors provide direct experimental evidence for an exchange band splitting that reaches 0.8 eV. This band splitting was found to show strong anisotropy and multiple nodal lines in momentum space associated with the PT symmetry breaking characteristic of altermagnets.