Study of exchange and anisotropy parameters versus insertion of H and C in the RFe11.35Nb0.65 compounds (R=Ho, Lu)

Magnetisation measurements were performed on oriented powder samples of the RFe11.35Nb0.65 compounds (R=Ho, Lu) and their hydrides and carbides. The study of the angular dependence of the parallel and perpendicular components of the magnetisation vector, reference to the applied field, allows to determine accurately the magnetocrystalline anisotropy parameters. Powder neutron diffraction experiments led to a determination of the crystallographic and magnetic structures of these materials, in particular the values of the iron and holmium moments on the different sites. Analysis of the results allowed estimation of the exchange interactions and of the magnetocrystalline anisotropy originating from both sublattices and an explanation of the spin reorientation process occurring in the Ho-based hydride.