Relation between Vortex Excitation and Thermal Conductivity in Superconductors

Thermal conductivity ${\kappa }_{xx}(T)$ under a field is investigated in $d_{x^2-y^2}$-wave superconductors and isotropic s-wave superconductors by the linear response theory, using a microscopic wave function of the vortex lattice states. To study the origin of the different field dependence of ${\kappa }_{xx}(T)$ between higher and lower temperature regions, we analyze the spatially-resolved thermal conductivity around a vortex at each temperature, which is related to the spectrum of the local density of states. We also discuss the electric conductivity in the same formulation for a comparison.