Mixed-Parity Altermagnetism in Collinear Spin-Orbital Magnets

TL;DR

This paper introduces mixed-parity altermagnetism in collinear spin-orbital magnets, revealing new symmetry conditions and demonstrating its induction via circularly polarized light, expanding the understanding of spin splitting phenomena.

Contribution

It identifies symmetry conditions for mixed-parity altermagnetism and demonstrates its realization in spin-orbital magnets through a two-sublattice two-orbital model.

Findings

Mixed-parity altermagnetism can occur in 2D spin-orbital magnets with mirror symmetry.

Circularly polarized light induces mixed-parity altermagnetism at finite staggered potential.

Mixed-parity altermagnetism exists between even- and odd-parity regimes with zero net magnetization.

Abstract

Altermagnetism has so far mainly been understood in its even- and odd-parity forms. We show that collinear antiferromagnets with zero net magnetization can also host mixed-parity spin splitting, namely neither purely even nor purely odd in momentum. We identify the symmetry conditions for such mixed-parity altermagnetism and show that, in two dimensions, it can arise in spin-orbital magnets when the two antiparallel spin sectors are related by a single mirror symmetry. Using a two-sublattice two-orbital model, we demonstrate that circularly polarized light induces mixed-parity altermagnetism at finite staggered potential and odd-parity spin-orbital altermagnetism at zero staggered potential. Mixed-parity altermagnetism thereby emerges as the intermediate spin-split regime between even- and odd-parity altermagnetism when spin splitting and zero net magnetization are maintained. Spin-resolved orbital Edelstein effects provide a complementary electrical probe of the underlying spin-orbital order.