A magnetic and Mössbauer spectral study of HoFe 11Ti and HoFe 11TiH

Abstract

A.c. susceptibility measurements were carried out between 4.2 and 295 K on HoFe 11TiH and reveal a spin-reorientation transition at ∼150 K. Iron-57 Mössbauer spectral measurements between 4.2 and 295 K were carried out on both HoFe 11Ti and HoFe 11TiH. The Mössbauer spectra were analyzed with a model which considers both the orientation of the iron magnetic moments and the distribution of titanium atoms in the near-neighbor environment of the three crystallographically distinct iron sites. The assignment and the temperature dependence of the hyperfine fields is in complete agreement with both the iron magnetic moments measured by neutron diffraction and the changes expected at the spin-reorientation. The assignment and the temperature dependence of the isomer shifts is in complete agreement both with the crystallographic changes occurring at the spin reorientation and upon hydrogen insertion. The changes in hyperfine field and isomer shift with the number of titanium near neighbors for each of the three iron sites are consistent with the values observed for related titanium–iron intermetallic compounds.