Magnetic, magneto-optical, and structural properties of URhAl from first-principles calculations

Abstract

We present a first-principles investigation of the electronic properties of the intermetallic uranium compound URhAl. Two band-structure methods are employed in our study, the full-potential augmented plane-wave (FLAPW) method, in which the spin-orbit interaction was recently implemented, and the relativistic, non-full-potential, augmented-spherical-wave method. To scrutinize the relativistic implementation of the FLAPW method, we compare the spin and orbital moments on each atom, as well as the magneto-optical Kerr spectra, as calculated with both methods. The computed quantities are remarkably consistent. With the FLAPW method we further investigate the magnetocrystalline anisotropy energy, the x-ray magnetic circular dichroism at the uranium ${M}_{4,5}$ edge, the equilibrium lattice volume, and the bulk modulus. The magnetocrystalline anisotropy energy is computed to be huge, 34 meV per formula unit. The calculated uranium moments exhibit an Ising-like behavior---they almost vanish when the magnetization direction is forced to lie in the uranium planes. The origin of this behavior is analyzed. The calculated optical and magneto-optical spectra, and also the equilibrium lattice parameter and bulk modulus, are found to compare well to the available experimental data, which emphasizes the itinerant character of the $5f$'s in URhAl.