Angular Momentum Compensation in Eu0.5Bi2.5Fe5-xGaxO12 Thin Films Prepared by Metal-Organic Decomposition Method

A large gyromagnetic ratio is crucial for the improvement of high-frequency magneto-optical (MO) properties, and it is expected to be achievable near the angular momentum compensation composition. In this study, Eu0.5Bi2.5Fe ${}_{5\text {-}x}$ GaxO12 thin films with varying gallium (Ga) substitution amounts were fabricated on Gd3Ga5O12 (GGG) (100) substrates using the metal-organic decomposition (MOD) method. These thin films were evaluated using MO spectroscopy and ferromagnetic resonance (FMR) measurement. MO measurements revealed a large Faraday rotation angle, accompanied by a reversal in the Faraday rotation spectrum between Ga substitution amounts of 1.1 and 1.2, indicating the presence of a magnetization compensation composition. In addition, FMR analysis showed an increased gyromagnetic ratio as Ga substitution increased from 1.0 to 1.1, suggesting the existence of an angular momentum compensation composition at room temperature.