Odd-parity altermagnets realized via Floquet engineering

Altermagnets (AMs), recently discovered unconventional magnets distinct from both ferro- and antiferromagnets, have rapidly emerged as a prominent research topic in condensed matter physics. AMs are characterized by alternating collinear magnetic moments with zero net magnetization in real space, and spin splittings with even-parity symmetry in momentum space. However, their counterparts exhibiting odd-parity spin splittings are generally thought to be absent in collinear magnets. Here, we show that such unconventional odd-parity magnets can be induced from collinear antiferromagnets by symmetry engineering. Remarkably, using effective model analysis within Floquettheory framework, we demonstrate that circularly polarized light irradiation of conventional antiferromagnetic lattices breaks a spin-preserving pseudo-time-reversal symmetry and induces both pand f-wave magnets, realizing novel magnetic states dubbed Floquet odd-parity collinear magnets. Moreover, we also uncover light-induced antiferromagnetic Chern insulating states in the f-wave magnets. The proposed Floquet odd-parity magnet is confirmed by first-principles calculations of MnPSe 3 under circularly polarized light. Our work not only proposes a new class of unconventional magnets, but also opens an avenue for light-induced magnetic phenomena in spintronic applications.