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Title:  Transport properties of anisotropic superconductors 
Author(s):  Arfi, Badredine 
Doctoral Committee Chair(s):  Pethick, C.J. 
Department / Program:  Physics 
Discipline:  Physics 
Degree:  Ph.D. 
Genre:  Dissertation 
Subject(s):  anisotropic superconductors
heavyfermion superconductors 
Abstract:  In some heavyfermion compounds (UPt3, and UBe13 under pressure) the normal state transport properties at low temperatures behave qualitatively as one would expect if electronimpurity interactions were the dominant source of scattering. The experimental data on ultrasonic attenuation and thermal conduction in the superconducting phase of UPt3 do not behave as one would expect if the electronimpurity phase shift were small, and therefore, assuming electronimpurity scattering to be the dominant process, we have calculated transport coefficients for a range of phase shifts, and for three anisotropic superconducting states, the axial and polar pwave states, and adwave state consistent with cubic and hexagonal crystal symmetries. We have calculated the amplitude for an impurity to scatter a quasiparticle by taking into account repeated scattering of a quasiparticle by a single impurity, and we find that for phase shifts which are not small the superconducting correlations can give rise to a very different energy dependence of the quasiparticle mean free path in the superconducting state, as compared with its behavior in the normal state. The calculated ultrasonic attenuation and thermal conductivity agree much better with the data for U Pt3 if the normalstate phase shift is taken to be resonant (close to 1r/2), and if the superconducting state has a nodal line at the equator of the Fermi surface. For phase shifts which are neither small, nor resonant, we find first, that the mean free times for quasiparticlelike excitations differ from the quasiholelike ones, which we show leads to an enhancement of the thermoelectric effect in the superconducting state by a factor of order TF fTc, and second, an angular asymmetry of the scattering amplitude with respect to reflection of the final momentum in the plane determined by the incoming momentum and the symmetry axis of the gap. This latter effect can occur if the superconducting state has nontrivial phase variations over the Fermi surface. The angular asymmetry leads to new tensor components of transport coefficients which are nonzero only if the parity of the superconducting order parameter is the same as that of the current or currents entering the transport coefficient. Experimental detection of these new coefficients would therefore serve to determine the parity of the order parameter. 
Issue Date:  1988 
Genre:  Dissertation / Thesis 
Type:  Text 
Language:  English 
URI:  http://hdl.handle.net/2142/28668 
Rights Information:  1988 Badredine Arfi 
Date Available in IDEALS:  20120120 
This item appears in the following Collection(s)

Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois 
Dissertations and Theses  Physics
Dissertations in Physics