Magnetoresistance, magnetic, and dielectric properties of LuFe2O4 prepared by ebeam-assisted solid state reaction

Abstract

We present structural, magnetoresistance, magnetic, Mössbauer, and dielectric properties of polycrystalline LuFe2O4 prepared by an electron-beam assisted solid state reaction. The x-ray diffraction pattern shows the single phase LuFe2O4 sample, and the ferrimagnetic transition temperature is measured at 240 K, followed by the two low-temperature transitions at 210 K and 140 K, respectively. The magnetic properties including the M-H hysteresis loops exhibit a strong temperature dependence and possibly indicate that LuFe2O4 enters a spin-glass state below 100 K. The iron Mössbauer measurement at 300 K indicates two Fe sites. The resistivity follows Mott’s variable-range hopping model, ρ∝exp(T0/T)1/4, indicating the electron hopping between Fe2+ and Fe3+. The magnetoresistance effects up to 2.5% at 5 T in the ferrimagnetic state were observed, and the effects could be caused by the field-induced changes in the electron hopping processes. The frequency-dependent complex dielectric constant has been found to be strongly influenced by the contact effects, and the intrinsic ferroelectricity of LuFe2O4 could not be ascertained.