Hyperfine interactions and electronic band structure in Tb0.27Dy0.73(Fe1−xNix)2 intermetallics

The consequences of Fe/Ni substitution in Tb0.27Dy0.73(Fe1−xNix)2 intermetallics, with a starting compound Tb0.27Dy0.73Fe2 known as Terfenol - D, were studied. Ni substitution introduces a local area, at sub-nanoscale, with different Fe/Ni neighbourhoods of the 57Fe atoms. 57Fe Mössbauer effect measurements for the intermetallic system Tb0.27Dy0.73(Fe1−xNix)2 carried out at 4.2 K evidence an [100] easy axis of magnetization. Hyperfine interaction parameters - an isomer shift, a magnetic hyperfine field and a quadrupole interaction parameter - were determined from the fitting procedure of the spectra, both for the local neighbourhood area and, as averaged values, for the sample as bulk. As a result of Fe/Ni substitution, a Slater-Pauling type dependence for the average magnetic hyperfine field vs. Ni content is observed. Electronic band structure calculations using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method were performed. The relation between the experimentally determined magnetic hyperfine field and the weighted magnetic moment calculated per transition metal atom is discussed.