Electric-Switchable Chiral Magnons in PT-Symmetric Antiferromagnets

TL;DR

This paper demonstrates that in PT-symmetric antiferromagnets, external electric fields can induce and control large magnon band splittings, enabling reversible spin current switching for advanced spintronic applications.

Contribution

It introduces a new class of PT-preserving antiferromagnets where electric fields induce significant magnon band splitting, a novel mechanism for magnon control.

Findings

Band splittings up to 20 meV in specific materials.

Electric field-induced reversible magnon spin current switching.

Identification of magnetic layer groups enabling this effect.

Abstract

The magnons in antiferromagnetic insulators (AFIs) exhibit dual chirality, each carrying opposite spin angular momentum. However, in PT-symmetric AFIs, 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 controlled by an external electric field. Unlike conventional 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. Group theoretical analysis identifies the possible magnetic layer groups, while first-principles calculations and spin-wave theory reveal band splittings up to 20meV in Cr2CCl2 and Cr2CBr2 under the electric field of 0.2 V/{\AA}, corresponding to an effective magnetic field of 200T. In addition, the electrically controlled magnon chiral splitting enables reversible switching of magnon-mediated spin currents. These findings open a new route toward nonvolatile spintronics based on magnons.