Thermal variation in magnetic properties of laser annealed Ga-substituted EuYIG films

Laser annealing makes available substituted bubble garnet films with identical composition but widely differing cation distributions. To investigate the thermal dependence of the magnetic properties of these films, we developed a high temperature bubble statics technique (293 to 440K), and employed variable temperature SQUID magnetometry (4.3 to 400K) and ferromagnetic resonance (∼7.5 to 293K). We have studied the variation of saturation magnetization (4πMs) and the uniaxial anisotropy constant (Ku) in laser-annealed, substituted EuYIG films from approximately 50K to each sample´s Curie temperature (Tc). In films (with identical composition) whose room temperature magnetizations vary by nearly 2:1, we find thermal dependencies for 4πMsthat support the simple cation exchange model for laser annealing. The temperature dependence of Kuis remarkably linear from 100K (below saturation of 4πMs) to about 50° below Tcin each sample, indicating a significant magnetostrictive contribution. Temperature stabilities of 4πMsand Q are also discussed.