Electrical resistivity and Moessbauer effect investigations on Tb0.27Dy0.73(Mn1-xFex)2 intermetallics

This paper concerns synthesis, X-ray analysis (300 K), electrical resistivity and 57Fe Moessbauer effect studies (4.2 K) of complete Tb0.27Dy0.73(Mn1-xFex)2 intermetallic series, with a borderline compound Tb0.27Dy0.73Fe2 known as Terfenol-D. A cubic Laves phase Fd3m of the MgCu2-type is observed across the series. The lattice parameter decreases parabolically with x. Electrical resistivity was measured in a wide temperature region across the Tb0.27Dy0.73(Mn1-xFex)2 series and the parameters which characterize resistivity dependence on temperature, including Debye temperature, were determined. Residual, phonon and magnetic contributions were separated from electrical resistivity. The magnetic contribution to electrical resistivity was applied to estimate Curie temperatures. The Curie temperature increases significantly with x. 57Fe Moessbauer effect measurements for the Tb0.27Dy0.73(Mn1-xFex)2 intermetallic system evidence an [1 0 0] easy axis of magnetization. Mn/Fe substitution introduces a local area, at sub-nanoscale, with different Mn/Fe neighbourhoods of the tested 57Fe atoms. Hyperfine interaction parameters, an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter were determined from the spectra both for the local neighbourhood area and, as averaged values, for the sample as bulk. The average magnetic hyperfine field increases parabolically with x. The correlation between Curie temperatures and magnetic hyperfine fields is discussed.