A. M. Boring

Fermi surface and effective masses for the heavy-electron superconductors UPt3

Local-density-approximation (LDA) calculations for the Fermi-surface extremal cross-sectional areas of UPt{sub 3} are presented and compared to deHaas-van Alphen experiments of Taillefer et al. The topology of the calculated surfaces is in excellent agreement with experiment and allows a determination of the directional dependence of the anisotropic mass-renormalization factor. The source of this renormalization is briefly discussed. 12 refs., 4 figs., 2 tabs.

Theory of the magneto-optic kerr-effect in NiUSn

Abstract An ab initio calculation of the electronic structure, optical conductivity and magneto-optic Kerr-effect is reported for the C 1 b phase compound NiUSn. Full relativistic spin-orbit interaction and spin polarization have been incorporated. The half-metallic behavior found earlier for this material has been effectively preserved with the inclusion of full spin-orbit coupling. The double polar Kerr angle, 2φ, is calculated to be about 10° in the infrared in about 4° in the visible spectrum and is found to be due to interband transitions.

Magnetism and bonding in light actinide and rare earth systems (invited)

The importance of including all of Hund’s rules in self‐consistent electronic‐structure calculations in solids is pointed out. We present a scheme that accounts for the interactions that lead to these rules, and we give examples of when these interactions become important. Calculated ground state properties (chemical bonding, magnetic moment, magnetic form factor) of actinide and rare earth systems are found to agree better with experiment when all Hund’s rules are accounted for. On the other hand, but also in agreement with experiment, we find that Hund’s second and third rule contributions for Fe, Co, and Ni are small.

Valance-Band photoemission intensities in thorium dioxide

Abstract Resonant photoemission spectra of the O 2p-derived valence band of insulating ThO2 are compared to linear muffin-tin orbital (LMTO) density-of-state (DOS) and XPS intensity calculations. At Th 5d corelevel threshold energies (85 ⩽ hv ⩽ 120 eV), resonance is greatest at the bottom of the O 2p band where calculated p/d hybrid states are greatest; p/f hybrid content is weak by comparison. We conclude that the dominant hybridization is between O 2p states and Th 6d.

Prediction of a large polar Kerr angle in NiUSn

An ab initio calculation of the magneto‐optic Kerr effect is reported for ferromagnetic NiUSn. The double polar Kerr angle 2Φ is predicted to be about 10° in the infrared and about 4° in the visible spectrum. It is concluded that substitutional alloys involving Clb phase materials and uranium atoms are important candidates for device applications.

First principles studies of crystal structures of f elements

Abstract The crystal structures of some selected f band metals (Ce, Th, Pa, U and Am) have been calculated from first principles. It is demonstrated that the onset of low symmetry structures correlates with the increasing f occupation of the valence states. It is also shown that pressure is an important parameter for these types of studies, and that the occupation of the various orbitals of the valence band depends on it. One can thus modify (increase) the f occupation of a certain system, simply by applying a pressure. Since the crystal structure depends on the f occupation, for these systems, one can drive different crystal structures as function of pressure. We present one such example, the FCC→BCT phase transition at ∼ Mbar for Th.

Electronic structure of the RBiPt compounds (RY and Yb)

Abstract The electronic structure of the semiconducting YBiPt intermetallic compound is compared with the isostructural, but metallic, YbBiPt compound. The difference in the transport properties is found to be governed by the volume, since the smaller volume in YbBiPt results in broader Yb d and Pt d bands and a closing of the semiconducting gap. The closing of the gap in YbBiPt is partly a relativistic effect, since scalar relativistic calculations do not reproduce the metallic ground state, whereas fully relativistic (Dirac) calculations do. In the semiconducting YBiPt intermetallic compound the valence band is found to be dominated by the Pt d states and the conduction band by the Y d states.

The one-electron picture of the actinide heavy-fermion superconductors

Abstract We have determined the electronic structure of the heavy fermion systems UBe13 and UPt3. These two systems in which the UU distances are very large do not exhibit local moment magnetism. That they are superconducting is also unusual for such large actinide separations. The electronic structure of UBe13 was calculated using the semi-relativistic LAPW method (spin-orbit included by solving the Dirac equation on the final interaction). The UPt3 electronic system was determined using the semi-relativistic LMTO method. The electronic structure of both systems was determined Self-consistently for the observed crystal structure at zero pressure. In both systems the electronic structure effectively separates into non-uranium bands and uranium bands. The uranium states near EF are dominated by the f bands pinned at EF. The calculated densities of states at EF, N(0), are at least one or two orders of magnitude lower than those inferred from experimental data.

ON THE PREDICTION OF FERROMAGNETISM AND METAMAGNETISM IN 4d TRANSITION-METAL OVERLAYERS

In this paper, the authors present theoretical evidence for ferromagnetism in Ru and Rh overlayers on Ag(001). These predictions are based on ab-initio, spin-polarized, electronic-structure calculations within the framework of the local spin-density approximation. For Tc, Ru, Rh, and Pd overlayers chemisorbed on Ag(001), only Ru and Rh exhibited ferromagnetism. Several metamagnetic spin states were found for the Ru overlayers.

Calculated XPS spectra of UIr3, UPt3 and UAu3

Using a single site approximation for the final state (LEED function) and classical electron-photon interaction the intensity of XPS spectra is calculated for UIr3, UPt3 and UAu3 in terms of relativistic LMTO partial densities of states and relativistic partial cross sections. For UPt3 and UAu3 the theoretical intensities compare very well with the available experimental data.