Light-induced magnetic anisotropy in Co-doped garnet films - art. no. 064405

Light-induced uniaxial magnetic anisotropy characterized by amplitude, time s of creation tau (1), and a vanishing tau (2) was studied. The investigati on was performed on YIG (yttrium iron garnet):Co,Ca,Ge Equid-phase epitaxy films using a very sensitive method-observation of changes of magnetic doma in structure with a different in-plane magnetization component induced by l inearly polarized light pulses. An argon laser (lambda =488 nm) was used. T he effective field H-L was introduced to describe the photoinduced uniaxial magnetic-anisotropy amplitude. These domain changes were studied within th e temperature range of 160-300 K. With an increase in temperature an increa se in tau (1), a decrease in tau (2), and a drastic decrease in H-L were fo und. The appearance of the photoinduced anisotropy is explained by light-in duced rearrangement of strongly anisotropic Co2+ octahedral ions. A microsc opic model was proposed where ion rearrangement is connected with electron excitations into the conducting band. Both thermal and light-induced excita tions were discussed. Numerical and analytical solutions of kinetic equatio ns describing the model are discussed. The dynamics of light-induced magnet ic anisotropy both uniaxial and cubic is analyzed.