Revealing the Altermagnetism in Hematite via XMCD Imaging and Anomalous Hall Electrical Transport

Altermagnets are a class of magnetic materials that exhibit unconventional transport properties, such as an anomalous Hall effect,despite having compensated sublattice magnetic moments. In this study, we report fundamental experimental evidence of the al-termagnetic nature of hematite (α-Fe2O3), combining electrical transport with advanced XPEEM imaging with linear and circulardichroism contrast. Our measurements directly visualize the N´eel vector’s coupling to the crystal orientation, confirming hematite’saltermagnetic order and its symmetry-driven transport behavior. Thetransport measurements reveal an anisotropic AHE with a pro-nounced crystal orientation dependence, including a sign inversion for specific N´eel vector alignments. Supported by first-principlestheoretical calculations, we explain how the interplay between collinear spin and crystal symmetry breaking drives the observedanomalous Hall effect. These findings establish hematite as an altermagnet, paving the way for experimental identification of alter-magnetic materials and their integration into spintronic technologies.