Magnetic anisotropy and sub-lattice magnetization study of polycrystalline magneto-electric Ga2−xFexO3

Polycrystalline magneto-electric Ga2−xFexO3 (0.8≤x≤1.2) ceramics are studied with bulk magnetization and 57Fe Mössbauer measurements. The ferrimagnetic to paramagnetic transition temperature (TC), saturation magnetization (MS) and the magnetic anisotropy values are found to vary significantly with the site-disorder of Fe3+ and Ga3+ cations. With the increase of iron content, increase of TC and MS, and decrease of magnetic anisotropy are observed. Using low temperature high magnetic field 57Fe Mössbauer measurements, individual temperature dependence of hyperfine fields and hence magnetization of the three sub-lattices are measured. It is observed that the three sub-lattices have quite a different temperature dependence resulting in the non-monotonous variation of resultant magnetization as measured by bulk magnetic measurements. Definite evidence, using 57Fe Mössbauer measurements, is submitted to show that the Fe ions at Fe2 and Ga2 sites are responsible for the observed magnetic anisotropy, site-disorder induced magnetism and thermo-magnetic irreversible features in Ga2−xFexO3.