Electronic Structure and Exchange Interactions in RNi4Co (R = Eu, Yb) Compounds

The electronic structure and the exchange interactions in EuNi4Co and YbNi4Co compounds have been calculated in terms of a theoretical approach with the inclusion of electronic correlations (LSDA + U method); the variants of substitution of cobalt ion for nickel in the 3d lattice in both types of crystallographic positions 2c and 3g are considered. The total energies obtained in self-consistent calculations show that individual cobalt impurities are more preferably arranged in position of the 3g type. A Co ion in RNi4Co (R = Eu, Yb) is characterized by a significant magnetic moment, which leads to significant increase in the exchange interaction of Co and Ni ions in the 3d metal sublattice.