Electronic band structure calculation and nuclear spin-lattice relaxation in chromium hydrides

Abstract

The angular-momentum components of the density of states (DOS) were calculated by the FP-LAPW method for stoichiometric CrH having either hexagonal (anti-NiAs) or cubic (NaCl or ZnS) types of structure. The shape of the DOS of the metal 3d states is remarkably similar for the two models of cubic structure, and differs only slightly from that for the hexagonal structure. The DOSs have been used to calculate the 53Cr nuclear spin-lattice relaxation rates. It is found that that the s and p electron contributions to the relaxation rates are negligibly small due to their very low partial densities of states at the Fermi level. The d-orbital contributions are dominant and the core-polarisation and d-dipolar contributions play a minor role. The experimental relaxation rates measured in hexagonal CrH 0.97 and CrH 0.93 and cubic CrH 0.97 indicated the presence of magnetic impurities in the samples, the contribution of which was subtracted from measured relaxation rates. It was found that the intrinsic relaxation rates are reasonably well reproduced by theoretical calculations.