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 Fe-57 Mossbauer measurements. The ferrimagnetic to paramagnetic transition temperature (T-C), saturation magnetization (M-S) 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 T-C and M-S, and decrease of magnetic anisotropy are observed. Using low temperature high magnetic held Fe-57 Mossbauer 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 or resultant magnetization as measured by bulk magnetic measurements. Definite evidence, using Fe-57 Mossbauer measurements, is submitted to show that the Fe ions at Fe-2 and Ga-2 sites are responsible for the observed magnetic anisotropy, site-disorder induced magnetism and thermo-magnetic irreversible features in (Ga2-xFeO3)-O-x. (C) 2014 Elsevier B.V. All rights reserved.