Altermagnets

3 problems

• Large tunneling magnetoresistance in all-altermagnetic tunnel junctions

  Open

  Theory predicts that a tunnel junction made only of altermagnets should change its resistance strongly when one electrode's spin pattern is reversed, giving a memory bit without ferromagnets. No experiment has yet shown this in a junction built only from altermagnets.

• Can electron interactions alone produce altermagnetism?

  Open

  Known altermagnets get their spin splitting from the arrangement of atoms in the crystal. Theory suggests that repulsion between electrons could create the same kind of spin-split state spontaneously, but no unbiased calculation has shown it in a simple model.

• Is RuO2 an altermagnet?

  Contested

  RuO2 was the first proposed metallic altermagnet, but muon and neutron measurements find no magnetic order in bulk crystals. Signals reported in thin films might come from surfaces or defects.