Detecting the hidden magnetism of altermagnets

Altermagnets are a newly recognized class of antiferromagnets whose magnetic structure behaves very differently from that found in conventional systems. In conventional antiferromagnets, sublattices are linked by simple inversion or translation, giving rise to spin-degenerate electronic bands. In altermagnets, however, they are connected by unconventional symmetries such as rotations or screw axes. This change in symmetry breaks spin degeneracy, allowing spin-polarized electron currents even in the absence of net magnetization.