Electron structure and spin dynamical properties of crystalline and amorphous rare-earth intermetallics from Moessbauer and μSR experiments

A comparative study of crystalline and amorphous DyAg using 161Dy Moessbauer spectroscopy is presented as a way to gain insight into the changes in electronic structure and spin dynamical properties of the rare-earth ion when its local surrounding is randomly distorted. It can be seen, especially in the paramagnetic regime, that the influence of the lowering of local symmetry is significant in both the electronic ground state of Dy3+ and the fluctuation rate of the local magnetic moment. At high-spin fluctuation rates, Moessbauer spectroscopy rapidly becomes insensitive, while muon spin relaxation (μSR) has still a high power of resolution. μSR measurements on Laves phase intermetallics are used to demonstrate the presence of paramagnetic spin correlations far above the Curie temperature. First measurements of this kind on crystalline and amorphous DyAg are also discussed. (Auth.)