Electronic structure and magneto-optical Kerr effect in UGa2

Abstract

The optical and magneto-optical (MO) spectra of UGa2 are investigated theoretically from first principles, using the fully relativistic Dirac linear muffin-tin orbital band structure method. The electronic structure is obtained with the local spin-density approximation (LSDA), as well as with generalization of the LSDA+U method which takes into account that in the presence of spin-orbit coupling the occupation matrix of localized electrons becomes nondiagonal in spin indexes. Although, the magnetic moment at the U site of UGa2 is described better by LSDA+U than by LSDA, neither the localized LSDA+U model nor the spin-polarized LSDA 5f-itinerant band model can explain all the peculiarities of the experimental MO spectra. The LSDA gives a better description of the optical and MO spectra of UGa2 in the 0–1 eV energy interval, but for higher energies the experimental Kerr rotation curve is situated someplace in between the curves obtained by the LSDA and the LSDA+U approximations. The origin of the Kerr rotation in the compound is examined.