From geometry-driven instabilities to topological superconductivity and spintronics

Altermagnets are a class of materials that possess a unique combination of magnetic and spatial symmetries. Despite having zero net magnetic moment due to fully compensated antiferromagnetic order, the hallmark feature of an altermagnet is nonrelativistic spin splitting in the electronic bands—a characteristic typically associated with ferromagnets. While their band structures are theoretically well understood, altermagnetic fluctuations and the formation of the corresponding instabilities remain largely unexplored.

Here, we establish a correspondence between the quantum metric in the normal phase and the altermagnetic spin splitting of the ordered phase, and show that the quantum metric favors altermagnetism. We further motivate that chiral magnons—the fundamental carriers of information in magnetic computers—arise similarly from the nontrivial quantum geometry found in altermagnets.

Even though these systems are not necessarily topologically nontrivial, we argue that they naturally tend toward p-wave superconductivity, and show how it can be induced by proximitizing an altermagnet with a conventional superconductor. Lastly, we discuss how superconducting altermagnets can be used to generate and transport persistent, spin-polarized supercurrents.