Photoinduced magnetic surface anisotropy field in YIG thin films

Abstract

Photoinduced changes in the spin wave spectrum of annealed pure YIG thin films have been measured at 23.3 GHz and positively identified as arising from a photoinduced magnetic surface anisotropy field. The effect depends upon the thermal history of the YIG thin film sample. For example, after cooling 20 K, illumination with white light (1.2 joules/cm2 or greater) reduces the resonance field separation of a surface spin wave mode and nearest body spin wave mode by 50% while the body mode incurs negligible shift. At 20 K, a photoinduced magnetic surface energy .0027 erg/cm2 is necessary to account and other measurements sensitive to the SWR boundary conditions. The measured photoinduced surface energy is an order of magnitude smaller at 175 K.