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arXiv · 2510.16248

Cavity-induced coherent magnetization and polaritons in altermagnets

Mohsen Yarmohammadi·Libor Šmejkal·James K. Freericks
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Abstract

Altermagnets feature antiparallel spin sublattices with $d$-, $g$-, or $i$-wave spin order, yielding nonrelativistic spin splitting without net magnetization. We show that embedding a two-dimensional $d$-wave altermagnet in a driven optical cavity induces a finite, tunable magnetization. Coherent photon driving couples selectively to electronic sublattices, and the resulting altermagnets' symmetry-broken spin texture yields a pronounced steady-state spin imbalance -- coherent magnetization -- absent in conventional antiferromagnets for the same lattice configuration. A mean-field Lindblad analysis reveals the dominance of quadratic over linear couplings. In the strong-coupling regime, distinct polariton signatures emerge in the steady state of induced magnetization. This work demonstrates cavity control of altermagnets for spintronic applications.

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Mohsen Yarmohammadi, Libor Šmejkal, James K. Freericks. 2025-10-17. Cavity-induced coherent magnetization and polaritons in altermagnets. https://doi.org/10.1103/7bss-9yxb

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