Completely Bi-Substituted Iron Garnet (BIG) Films Prepared by Electron Cyclotron Resonance (ECR) Sputtering

Completely Bi-substituted iron garnet (BIG) films were epitaxially synthesized on garnet substrates by electron cyclotron resonance (ECR) sputtering. The critical temperature for the epitaxial growth, crystallinities, and Faraday rotation θF of BIG films depend on the O2 gas flow rate. With an optimum flow rate of 7 sccm, single-crystal BIG films were obtained at temperatures above 390°C, and θF achieved its largest value of 8.4×104 deg/cm (λ=0.633 µm). The minimum ferromagnetic resonance (FMR) linewidth ΔH was 70 Oe; this is the smallest value ever reported. The uniaxial perpendicular magnetic anisotropy is mainly caused by the elastic deformation induced by the thermal expansion mismatch between the film and the substrate.