Unveiling altermagnetism: spin splitting and magnetotransport in MnTe

Altermagnets are a novel class of compensated collinear magnets distinct from ferro- and antiferromagnets. Their opposite sublattices are related by rotational symmetry, leading to time-reversal symmetry breaking and an alternating spin splitting in the Brillouin zone. We experimentally verify this spin splitting in MnTe using angle-resolved photoemission spectroscopy. The characteristic band structure enables linear responses such as the anomalous Hall effect and X-ray magnetic circular dichroism, alongside even responses like anisotropic magnetoresistance and magnetic linear dichroism. A combination of X-ray linear and circular dichroism techniques allows for nanoscale imaging of domain patterns, providing further insights into altermagnetic properties.