F. M. Mueller

Pressure dependence of the electronic structure and Fermi surface of palladium

Abstract We have considered the effects of hydrostatic pressure on the de Haas-van Alphen external cross-sectional areas of the Fermi surface of palladium. Our calculations for the density of states in palladium with extended and contracted lattice constants show that a change of 2 per cent in the lattice constant changes the density of states at Fermi energy by 10 per cent.

Fermi velocity and Fermi radius in platinum

Abstract A new technique for determining the Fermi velocity in metals has been developed. Using this technique we determine the Fermi velocity for the Γ-centered surface of Pt.

Anisotropic g Factors of Nickel, Palladium, and Platinum

The effective g factors of states on all sheets of the Fermi surface for fcc paramagnetic nickel, palladium and platinum have been considered. Calculations have been carried out using both the combined interpolation scheme and the Symmetrized Relativistic Augmented Plane Wave (SRAPW) methods. Corrections due to the outside of the muffin‐tin spheres potential (included for Pd and Pt) are shown to be small. Strong spin quenching in all three systems is caused by combination of the close proximity of the dominant X5 and L3 (single group representation) levels to the Fermi energy and the raising of their degeneracies by the important spin‐orbit interaction. Comparisons with the experimental data, in particular static susceptibility and dHvA orbital g factors, are presented.

Knight Shifts in Transition Metals

Analyses of Knight shifts (K) in transition metals commonly assume that the s and d bands are distinguishable at the Fermi energy (i.e., small s‐d hybridization). The three major contributions to K are attributed to unpaired s electrons (Ks), unpaired d spins (Kd) and orbital angular momentum (Korb) each arising from counterpart terms in the susceptibility, χ. This partitioning (valid for weak spin‐orbit interactions) allows one to relate the s and d contributions to χ to the corresponding densities Ns(EF) and Nd(EF). One further assumes that Ns(E) varies much more slowly than Nd(E) so that the d‐spin susceptibility is the only temperature‐dependent term. The free‐electron description is then used to calculate Ks. We report here investigations of contributions to Knight shifts (and relaxation rates) using ab initio SRAPW band calculations, the combined interpolation scheme and the QUAD scheme. Strong s‐d hybridization is found to cause substantial structure in the projected Ns(E) for fcc Ni, Pd and Pt, as...

Accurate Orientation Method for dHvA Data

A new technique for improving the accuracy of the angular orientation of nonsymmetry plane dHvA data on cubic systems by an order of magnitude (from 2.0° to 0.2°) has been developed. The extension of this technique to orienting dHvA data in noncubic crystallographic systems, or to orienting data for other types of experiments, viz. neutron scattering, should be straightforward.

Electronic Structure and Magnetic Properties of Scandium

The Van Vleck orbital and Pauli spin paramagnetic contributions to the magnetic susceptibility of single crystal and polycrystalline scandium are calculated using the APW method in conjunction with an LCAO interpolation scheme, which uses s, p and d type functions in the tight‐binding representation. The warped muffin‐tin APW potential was obtained from overlapping charge densities which were derived from the atomic configuration 3d24s; the exchange interaction was included in full Slater ρ1/3 approximation. The Fermi energy is found to lie in a sharp peak in the density of states curve. The anisotropy in the magnetic susceptibility and the low temperature variation of the susceptibility of scandium, particularly the hump around 25°K observed by Spedding and Croat,1 are succesfully explained. The large enhancement of the low‐temperature specific heat due to spin flucutations calculated from the molecular field parameter in RPA approximation is shown to account for the absence of superconductivity in scandium.

Wannier Representation of Electron Energy Bands and Iron Fermi Surface

For the first time Fourier inversion of the real energy bands has been performed. About 1000 inequivalent coefficients are obtained. It appears that about six nearest neighbors are important in metallic iron. The coefficients have been used to calculate FS. Spin‐orbit interactions showed profound influence on the topology of FS in Fe.