Magnetic and 57Fe Mössbauer study of magneto-electric GaFeO3 prepared by the sol–gel route

Abstract

This work reports the preparation of magneto-electric GaFeO3 by the sol–gel route and its characterization by x-ray diffraction, dc-magnetization, ac-susceptibility, low temperature and high field 57Fe Mössbauer spectroscopy and dielectric constant measurements. The prepared samples are found to be single phase from x-ray diffraction studies. The crystallite sizes are found to be in the nano-regime for the samples sintered at low temperatures. From the temperature dependent dc-magnetization (M–T) measurements, bifurcation of the zero-field cooled (ZFC)–field cooled data and a cusp in the ZFC data are observed. With the help of low-field ac-susceptibility, 57Fe Mössbauer and detailed dc-magnetic measurements these features are explained in terms of the magnetic anisotropy of the sample ruling out phenomena like spin-glass and super-paramagnetism as quoted in the literature for this compound. Apart from this, very interesting and different M–H behavior mimicking composite two-phase magnets is observed for the samples sintered at different temperatures. A symmetric M–H loop is observed for samples sintered at low temperatures and a pinched M–H loop is observed for samples sintered at high temperatures. The observed magnetic properties are explained by estimating the Fe cation distribution using high field 57Fe Mössbauer spectroscopy measurements. An anomaly in the dielectric constant data at the Curie temperature indicates the ME coupling of the samples.