THEORY OF THERMAL CONDUCTIVITY OF HIGH TEMPERATURE SUPERCONDUCTORS: A NEW APPROACH

Abstract

An ab initio formulation of relaxation times of various contributing processes have been observed with newer understanding in terms of electron and phonon line widths. This is dealt with the help of double time temperature-dependent Green's function via a non-perturbative approach using a crystal Hamiltonian which comprises of the effects of electrons, phonons, impurities, anharmonicities and interactions thereof. The frequency line widths is observed as an extremely sensitive quantity in the transport phenomena of high temperature superconductors (HTS) as a collection of a large number of scattering processes, namely: boundary scattering, impurity scattering, multi-phonon scattering, interference scattering, electron–phonon processes and resonance scattering. The behavior of electrons and phonons is then investigated to describe the thermal conductivity of a variety of HTS samples specially in the vicinity of transition temperature to successfully explain the spectacular dip region of thermal conductivity curve which was lacking in explanation earlier with a sound physical justification.