We identify a nonequilibrium route for generating altermagnetic spin splitting in antiferromagnet by ultrafast light. Unlike existing strategies, this route does not require relativistic angular-momentum transfer, static symmetry breaking, or auxiliary external fields. Using real-time time-dependent density functional theory, we demonstrate in the antiferromagnetic perovskite KNiF3 that linearly polarized light can induce momentum-dependent altermagnetic spin splitting by breaking the effective time-reversal symmetry through photoexcited charge redistribution and the resulting lattice distortion. We provide a general symmetry selection rule for this route. These results establish a mechanism for ultrafast control of altermagnetism and extend its material realization into the nonequilibrium regime.
@article{arxiv.2604.02790,
title = {A Route to Nonrelativistic Altermagnetic Spin Splitting via Ultrafast Light},
author = {Huang-Zhao-Xiang Chen and Lin-Ding Yuan and Wen-Hao Liu and Lin-Wang Wang and Jun-Wei Luo and Zhi Wang},
journal= {arXiv preprint arXiv:2604.02790},
year = {2026}
}