In condensed matter physics, altermagnetism is a type of persistent magnetic state in ideal crystals. Altermagnetic structures are collinear and crystal-symmetry compensated, resulting in zero net magnetisation. Unlike in an ordinary collinear antiferromagnet, another magnetic state with zero net magnetization, the electronic bands in an altermagnet are not Kramers degenerate, but instead depend on the wavevector in a spin-dependent way.  Related to this feature, key experimental observations 
were published in 2024. It has been speculated that altermagnetism may have applications in the field of spintronics.