James C. Swihart

Theory of the contribution of the electron-phonon interaction to the anisotropic electronic lifetime and transport properties of zine

Using pseudopotential theory for the phonons, electrons, and electron-phonon interaction of zine, we have calculated several electronic properties of this metal. Among these are the electron lifetime at three positions on the Fermi surface, the anisotropic electrical resistivity, the anisotropic thermal conductivity, and the ultrasonic attenuation, all due to the electron-phonon interaction, and all as a function of temperature. For the electrical resistivity, two solutions of the Boltzmann equation were obtained, one consisting of a single spherical harmonic, and the other made up of six spherical harmonics. The single spherical harmonic is not adequate at low temperatures.

Influence of transport corrections on the infrared absorption in superconductors

Abstract In order to study the magnitude of the vertex correction in the infrared absorption in a superconductor, we have calculated the and ω dependent response function for a simple Debye model of a superconductor. We have carried out our calculations for no vertex correction and also for the first vertex correction in both the high q and low q limits. The vertex correction calculation includes the influence of transport modifications due to the interference between quasiparticle scattering by phonons and the quasiparticle-external field interaction. This correction is small for all frequencies except those just above the gap. Our calculations indicate that, with vertex corrections, the theory for lead would be in even better agreement with experiment.

Calculation of the thermopower of Ni-P amorphous alloys

We have modeled the Ni-P amorphous alloy system by a set of supercells on which we have carried out calculations of electronic and transport properties. The thermopower is determined by calculating the energy dependence of the dc electrical conductivity from the Kubo formalism. At 15% P we find {minus}0.015 {mu}V/K{sup 2} for the thermopower divided by the temperature, while for 25% P the calculated value is +0.008 {mu}V/K{sup 2}, in reasonable agreement with experiment, particularly with regard to the change of sign with concentration.

Anisotropy of the enhanced electron mass in indium

Abstract We have calculated the mass enhancement λ k due to phonons as a function of position along the central [110] cyclotron orbits on the second and third zone Fermi surfaces in indium. The third zone λ k are about 50% larger than those on the second zone in good agreement with cyclotron mass measurements.

Vertex corrections in infrared absorption in superconducting and normal metals

Abstract We have calculated the frequency dependent electromagnetic absorption in both the superconducting and normal states for a model of a strong-coupling superconductor. We have done this in the absence of vertex corrections and also with the inclusion of vertex corrections in a certain approximation. We find that in the range of phonon energies the vertex correction is quite small for the normal state. The same is true for the superconducting state except near the gap. This correction tends to bring the theory into closer agreement with experiments on the absorption in Pb.

Resistance peak at the superconducting transition of thin films of tin and indium

Abstract A narrow resistance peak as a function of temperature and magnetic field has been found at the superconducting transition for thin films of tin and indium. The effect is greatest for film thicknesses near the coherence length.