Antiferroaxial altermagnetism

TL;DR

This paper introduces antiferroaxial altermagnetism as a new, broadly applicable multiferroic mechanism that links antiferroaxial order with reversible spin splitting, supported by theoretical models and material screening.

Contribution

It establishes the symmetry-based mechanism of antiferroaxial altermagnetism and identifies candidate materials, advancing the understanding of multiferroic spintronic control.

Findings

Reversal of antiferroaxial order switches spin splitting.

Symmetry-allowed trilinear coupling identified.

Candidate materials screened from databases.

Abstract

The antiferroaxial state is emerging as an important ferroic order in condensed matter systems. Here, we establish antiferroaxial altermagnetism as a broadly prevalent, generic, and microscopically grounded multiferroic mechanism, in which antiferroaxial counter-rotating distortions both induce altermagnetism and enable its deterministic and reversible switching. Within a unified Landau-theory and symmetry framework, we identify a symmetry-allowed trilinear invariant coupling the antiferroaxial order, the N\'{e}el vector, and the altermagnetic order, and derive general symmetry criteria for its occurrence. This coupling locks the induced altermagnetism to the antiferroaxial order, so that reversing the latter reverses the spin splitting and associated time-reversal-odd responses, such as anomalous Hall conductivity. We provide a practical spin group dictionary mapping N\'{e}el-vector representations to the resulting $d$-, $g$-, and $i$-wave antiferroaxial altermagnetism, validate the mechanism with ligand-rotation tight-binding models and first-principles calculations, and identify many candidate materials by screening the MAGNDATA and C2DB databases. Our results elevate antiferroaxiality to a universal ferroic control knob for structurally programmable altermagnetic spintronics.