Magnetic properties of Ga:YIG with laser irradiation in inert gas

Magnetic properties of substituted iron garnet films can be changed locally by laser irradiation (annealing and quenching ). We have investigated laser annealing with furnace back-up heating in O2, N2and Ar gas over a wide range of temperature. In air, laser annealing with high temperature back-up heating above 700°C resulted in domain width reduction with both Msand Kuincreased differing from other reports. In inert gas, laser annealing with rather low temperature back-up heating is expected to vary magnetic properties locally which is different from that produced by high temperature heating since produced oxygen vacancies lower the activation energy and the relaxation time for cation migration. Only with back-up heating below 650°C, we succeeded high quality annealing in inert gas. Our re-annealing experiment of this film showed that low temperature laser annealing might have lowered the saturation magnetization which is not performed in air. We have found wide temperature range of reversible laser annealing.