First-principles calculation of hyperfine fields in ternary compounds and their carbides

Abstract

The Fermi contact magnetic hyperfine fields in compounds (x = 0, 2, 4) and in and carbides are calculated self-consistently by the TB-LMTO method using two types of approximation for the exchange-correlation potential. For , the calculated magnitude of the hyperfine field is close to the experimental one. The proportionality of the average hyperfine field to the vanadium content in observed experimentally over the narrow concentration range x = 1.5-2.8 is not reproduced for the limiting concentrations x = 0 and 4. The hyperfine fields at Fe atoms at crystallographically non-equivalent sites of the unit cells are analysed. It is proved that the assumption of proportionality of the hyperfine field to the local magnetic moments of Fe atoms is not justified in the cases of the compounds investigated. It is shown that, though the local Fe magnetic moments for all compositions satisfy the relation , the hyperfine field at the Fe at the 8( j) positions of the unit cell has the lowest magnitude for all of the compounds. Analysis of the different components of has revealed that the opposite variation in the hyperfine field with the 3d local magnetic moment is due to the hybridization interaction of the 4s valence electrons with the spin-polarized d shell of the surrounding atoms.