Quantum oscillation studies of altermagnet candidates

Altermagnets are characterized by a compensated collinear magnetic ordering that alternates both in the crystal structure in direct (real) space, and throughout momentum (reciprocal) space. This leads to a spin-split electronic bandstructure that breaks time-reversal symmetry. Quantum oscillation measurements have been proposed as an ideal diagnostic tool for identifying the lifting of Kramers spin degeneracy in such materials. This talk will review recent measurements on candidate altermagnets. While our quantum oscillation measurements have robustly ruled out altermagnetism in RuO₂, the lifting of Kramers spin degeneracy is clearly apparent in the bulk-resolved electronic band structure of CrSb – earmarking it as a prototypical metallic altermagnet.