Mössbauer studies of GdFe_2-xHf_x alloys

GdFe_2-xHf_x alloys, where x = 0, 0.10, 0.15, 0.20, and 0.30, are produced by arc-melting of pure elements. The samples are investigated by x-ray diffraction and Fe⁵⁷ Mössbauer spectroscopy at 78 K and 300 K. We find that the alloy system GdFe_2-xHf_x have the single phase cubic Cu₂Mg type structure in the whole concentration range. Mössbauer spectroscopic results show that all the samples studied are magnetically ordered at 78 K, and at room temperature. The room temperature spectra are fitted with two magnetic components where the direction of magnetization is along the [111] while the spectra at 78 K are fitted with four magnetic subspectra indicating a complex direction of magnetization for all samples under investigation. The average magnetic hyperfine field and the average isomer shift are found to decrease almost linearly with increasing the Hf concentration at 78 K and 300 K due to the replacement of Fe by nonmagnetic Hf.