Antiferromagnetic spin dynamics is crucial for developing spintronic devices. This study uses ab initio nonadiabatic molecular dynamics with spin-orbit coupling (SOC) to investigate photoinduced spin dynamics in an antiferromagnetic semiconductor MnPS₃ monolayer. Optical doping triggers a phase transition from Néel antiferromagnetic to ferromagnetic at an electron-hole pair density of 1.11 × 10¹⁴ cm⁻². This is due to light-induced mid-gap states of S-p orbitals, strengthening SOC between S-p and Mn-d orbitals. Excited S-p electrons decay to mid-gap states via p-p electron-phonon coupling and then relax to spin-down Mn-d orbitals via SOC. This relaxation prolongs the carrier lifetime to 648 fs, explaining MnPS₃'s optoelectronic performance. Reversible magnetic order switching via optical means is significant for information storage and photocatalysts using antiferromagnetic semiconductors.

Yinlu Gao, Xue Jiang, Zhiyong Qiu, Jijun Zhao