Effect of optical irradiation on the indirect exchange constant of a magnetic impurity system and an antiferromagnetic insulator

Abstract

Based on a multisite s-d mixing model, in which electron-photon coupling was taken into account, a scheme to calculate the indirect exchange constant of a magnetic impurity system and an antiferromagnetic insulator in thepresence of radiation field was advanced. The effect of optical irradiation on the exchange constant was calculated within a single valence model for imperfect NiO. A notable change of antiferromagnetic exchange interaction occurs while ‖S d , i ‖ 2 N p q is larger than 1.0×10 - 4 (eV) 2 (S d , i is the transition matrix element between a d state and an impurity state, and N p q is photon population). The decrease of antiferromagnetic exchange interaction reaches about 10% in the radiation field provided by a typical pulsed laser source while there exist appropriate impurity states in the imperfect NiO. The effect can be used to explain the photoinduced decrease of pinning strength in NiO/FeNi bilayer.