Structural, magnetic and mössbauer studies of GdFe_xMn_1-xO₃ multiferroic materials

GdFe_xMn_1-xO₃ (x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) nanoparticle series was synthesised using sol–gel auto-combustion technique. Rietveld refinement of x-ray diffraction (XRD) patterns revealed that all samples are crystallized in a single phase with (Pnma) space group No.62. The FC–ZFC measurements showed an increase in the antiferromagnetic (AFM) to paramagnetic (PM) transition Néel temperature (T_N) with the increase of Fe³⁺ content, reaching a value of 344 K at 50% of Fe doping. The inclusion of Fe also induced spin reorientation temperature (T_SR) at x = 0.5 and x = 0.7. ⁵⁷Fe mössbauer spectroscopy measurements were carried out at room temperature (RT⁓295 K) and liquid nitrogen (LN⁓78 K) temperature. Both RT and LN mössbauer spectra were fitted with paramagnetic doublet for low Fe content (x < 0.5), whereas for higher Fe content (x > 0.5), the spectra were fitted with magnetic sextet. Isomer shift values confirms the dominance of Fe in its high oxidation state (Fe³⁺).