Photomagnetic Anneal, A New Magneto-Optic Effect, in Si-Doped Yttrium Iron Garnet

Experimental evidence is given to show that the magnetocrystalline anistropy of silicondoped yttrium iron garnet, nominal composition ${\mathrm{Y}}_3$ ${\mathrm{Fe}}_{4.9}$ ${\mathrm{Si}}_{0.1}$ ${\mathrm{O}}_{12}$, can be changed by more than 100 Oe at 20°K through irradiation with near-infrared photons. The change is interpreted as due to the redistribution of electrons between iron ions, that is valence exchange.