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 ͑FLAPW͒ method, in which the spin-orbit interaction was recently implemented, and the relativistic, non-fullpotential, 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 Isinglike 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 5 f 's in URhAl.

X-ray magnetic circular dichroism experiments and theory of transuranium Laves phase compounds

“…This asymmetric spectral shape, like for the M 5 -edge of U, depends strongly on the hybridization, Coulomb, exchange, and crystal-field interactions. We will see in section IV that within a band structure model, this asymmetry can be well explained [39].…”

“…In the experimental spectra there has an s-shape, starting with negative values, switching the sign to a positive peak and monotonously decreasing to zero. The origin of such an XMCD shape has been outlined previously [39].…”

“…For a description of the implementation in the FLAPW basis we refer to Refs. [39,60]. Figure 11 summarizes the resulting XAS spectra of NpOs 2 and their difference -the XMCD.…”

“…There have also been a number of theory efforts calculating the band structures and comparing the resulting XAS and XMCD signals with experiment [34][35][36][37][38][39]. Using atomic theory, Thole and Carra [40][41][42] have derived sum-rules that relate integrated intensities of XAS and XMCD to the ground-state expectation values of standard operators, such as the orbital L z and spin S z magnetic moments of the absorbing atom.…”

Influence of the crystal structure of thin Co films on X-ray magnetic linear dichroism—Comparison of ab initio theory and reflectometry experiments

“…The spin-orbit interaction (SOI) was included in a second-variation scheme. 10 The following parameters were employed: the energy cutoff, given as the product of the muffin-tin radius and the maximum reciprocal space vector was R MT K max ¼ 8.5, the largest reciprocal vector in the charge Fourier expansion, G max , was set to 14 Ry 1/2 , and the maximum value of partial waves inside the muffin-tin spheres, l max ¼ 10. The Brillouin zone sampling was done on grid of 27 Â 27 Â 27 (22 Â 22 Â 11) k-points for the fcc (hcp) structure, whereas for the squared momentum matrix elements among all band and k-wave vectors combinations corresponding to the optical transitions, 11 a finer mesh of 81 Â 81 Â 81 (44 Â 44 Â 22) was used, respectively.…”