Hartree-Fock study of orbital magnetic moments in 3d and 5f magnets and X-ray magnetic circular dichroism.
The spin (Ms) and orbital magnetic moments (Mo) of the uranium 5f state in the ferromagnetic compound uranium sulfide (US) and of the cobalt 3d state in various transition-metal superlattices are calculated on the basis of a tight-binding model, in which the intra-atomic f-f or d-d multipole interaction is taken into account using the Hartree-Fock (HF) approximation. The parameters in the model are determined on the basis of available first-principles calculations. For US, the calculated ratio Mo/Ms and magnetic circular dichroism spectrum for U M4,5 absorption are in good agreement with the experimental results. Inclusion of the expectation values of the spin-off-diagonal operators in addition to the number operators in the 5f state is found to be crucially important when describing the 5f magnetic state. A difference in enhancement of Mo of the Co atom between the Co/Pd and Co/Cu superlattices is discussed on the basis of a semi-quantitative calculation, assuming ferromagnetism.
Jo
T
T
Department of Quantum Matter, Hiroshima University, Higashi-Hiroshima, Japan. jo@sci.hiroshima-u.ac.jp