Direct experimental evidence of altermagnetic band structure in semiconducting MnTe and metallic RuO was first published in 2024. Many more materials are predicted to be altermagnets – ranging from insulators, semiconductors, and metals to superconductors.  Altermagnetism was predicted in 3d and 2d materials with both light as well as heavy elements and can be found in nonrelativistic as well as relativistic band structures.