Электронная структура и обменные взаимодействия соединений RNi-=SUB=-4-=/SUB=-Co (R=Eu,Yb)

The electronic structure and the exchange interactions in EuNi_4Co and YbNi_4Co 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 3 d lattice in both types of crystallographic positions 2 c and 3 g are considered. The total energies obtained in self-consistent calculations show that individual cobalt impurities are more preferably arranged in position of the 3 g type. A Co ion in RNi_4Co (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 3 d metal sublattice.