Altermagnets, recently discovered unconventional magnets distinct from both ferro- and antiferromagnets, have rapidly emerged as a prominent research topic in condensed matter physics. Altermagnets 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 a Floquet-theory framework, we demonstrate that circularly polarized light irradiation of conventional antiferromagnetic lattices breaks a spin-preserving pseudo-time-reversal symmetry and induces both $p$- and $f$-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 ${\mathrm{MnPSe}}_3$ under circularly polarized light. Our Letter not only proposes a new class of unconventional magnets, but also opens an avenue for light-induced magnetic phenomena in spintronic applications.

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• Magnetism
• Altermagnets
• Chern insulators
• Magnetic systems
• Bloch-Floquet theorem
• First-principles calculations