Electric-Switchable Chiral Magnons in PT-Symmetric Antiferromagnets

Abstract: The magnons in antiferromagnetic insulators (AFIs) exhibit dual chirality, each carrying opposite spin angular momentum. However, in AFIs that are protected by PT symmetry, the magnon bands remain degenerate. In this work, we introduce a new class of PT - preserving AFIs in which the giant chiral splitting of magnons can be induced and reversibly controlled by an external electric field. Unlike ordinary cases, such AFIs host a hidden dipole coupled to the antiferromagnetic order, which allows an external electric field to break the magnon sublattice symmetry and thereby largely lift the band degeneracy. Through group theory analysis, we identify the possible magnetic layer groups that support electric-field-induced magnon band splitting. Promisingly, by density-functional- theory and spin wave calculations, the magnon band splitting of Cr2CBr2 reach up to 27meV induced by an electric field of 0.2V/Å, equivalent to the 230T under a uniform magnetic field. In addition, since chiral splitting is directly coupled to the electric field, the corresponding magnon-mediated spin current can be switched by the electric field. Our Letter opens a door for developing electric-field-controlled spintronics based on the magnons.