Type
Text
Type
Dissertation
Date
2009-08-01
Keywords
Low temperature thermal conductivity | Thermal conductivity | Superconductors
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/71070
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
The low energy excitations of cuprate superconductors are Dirac fermions which arise due to the d-wave nature of the superconducting order parameter. At low temperatures, these quasiparticles lead to a striking prediction of a universal thermal conductivity, κ00, which is independent of disorder.The universality of the low temperature thermal conductivity is not always observed, however, in the underdoped region of the phase diagram for several materials. In this region, the situation is complicated by evidence of coexisting order parameters, such as charge and spin density waves. These competing orders may be responsible for suppressing the universal limit thermal conductivity via their effect on the quasiparticle spectrum. In this thesis we present the two following results. First, we suppose the addition of a Q = (π, 0) charge density wave to a d-wave BCS-like superconductor. At low temperatures, where impurities are the dominant scattering mechanism, we calculate the thermal iii conductivity, including the effects of vertex corrections within the self-consistent Born approximation. Using the results of the previous calculation, which indicates that simpler bare-bubble results are adequate to describe the thermal conductance, we proceed to write a mean-field description of a dwave superconductor in the presence of a variety of density waves. By calculating the effect of these competing orders on the quasiparticle spectrum and comparing it to the low-temperature thermal conductivity, we examine the way in which the universal limit thermal conductivity is affected by the incipient density waves. In general, the presence of competing orders induces disorder dependence in κ00, and can suppress it entirely given sufficient amplitude of density wave.
Recommended Citation
Schiff, Philip Ross, "Low Temperature Thermal
Conductivity and Competing Orders
in d-wave Superconductors" (2009). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 277.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/277