THEORETICAL ASPECTS OF THE MAGNETISM IN THE FERROMAGNETIC AFE2 SYSTEMS (A = U, NP, PU, AND AM)

We report on spin-polarized energy-band calculations for the cubic Laves-phase systems UFe2, NpFe2, PuFe2, and AmFe2. The calculations were performed with the local-density approximation for the exchange and correlation potential together with a term that shifts the one-electron eigenvalues and takes into account the different interelectronic repulsions for electrons with different 5f magnetic quantum numbers. The spin-orbit interaction was also included in the band Hamiltonian. Thus the parameter-free calculations incorporate Hunds first, second, and third rules. The magnetism in the first three compounds was found to be dominated by a large orbital contribution coupled antiparallel to the spin moment. In the calculations for AmFe2, the 5f electrons were treated as core electrons. The magnetism was here found to behave very much like the magnetism of similar rare-earth Laves-phase compounds. © 1990 The American Physical Society.