A metallic room-temperature d-wave altermagnet

Abstract

Altermagnetism is a recently discovered unconventional magnetic phase that is characterized by time-reversal symmetry breaking and spin-split band structures in materials with zero net magnetization. Recently, spin-polarized band structures and a vanishing net magnetization were observed in semiconductors MnTe and MnTe2, confirming this unconventional magnetic order. Metallic altermagnets offer advantages for exploring physical phenomena related to low-energy quasiparticle excitations and for applications in spintronics because the finite electrical conductivity of metals allows direct manipulation of the spin current through the electric field. We demonstrate that KV2Se2O is a metallic room-temperature altermagnet with d-wave spin-momentum locking. Our experiments probe the magnetic and electronic structures of this compound and reveal a highly anisotropic spin-polarized Fermi surface and the emergence of a spin-density-wave order in the altermagnetic phase. These characteristics suggest that KV2Se2O could be a helpful platform for high-performance spintronic devices and for studying many-body effects coupled with unconventional magnetism. Metallic altermagnets are promising for applications due to the spin-polarized electric current that originates from their spin-split band structure. Now d-wave altermagnetism with antisymmetric spin polarization has been demonstrated in KV2Se2O.