Diamond quantum sensor could reveal elusive altermagnets

For nearly a century, there were two known kinds of magnets. Ferromagnets are the classic magnets that attract metal and keep pictures stuck to the refrigerator. Antiferromagnets hide their magnetism at the atomic scale but are increasingly prized for their technological potential. A third category discovered within the last decade may combine the best qualities of both. Dubbed altermagnets, they could someday help create faster, more energy-efficient electronics.