ANALYSIS OF HEAT CAPACITY OF YBa2Cu3O7-δ SUPERCONDUCTORS: ROLE OF LATTICE AND ELECTRON CONTRIBUTION

Abstract

Observed temperature-dependent heat capacity C (T) behavior of high-Tc YBa 2 Cu 3 O 7-δ cuprate superconductors has been theoretically analyzed in the temperature domain 70 ≤ T ≤ 110 K . Calculations of C (T) have been made within the two component scheme: one is the Fermionic term and the other the Bosonic (phonon) contribution. While estimating the electronic term, we use a mean field step and follow two-fluid model below and above Tc. Later on, the lattice heat capacity is estimated within harmonic approximation for high temperature expansion (T > θ/2π), the model has only one free parameter, the moments of phonon density of states. Within the two-fluid model for electronic specific heat along with reported γ value leads to a sharp discontinuity at Tc. The Coulomb correlations and electron-phonon coupling strength have significant implications on the γ. Henceforth, the present numerical analysis of specific heat from the present model shows similar results as those revealed from experiments. The accurate fitting of the specific heat data reveals that it is possible to decompose the documented specific heat into dominant lattice contribution and electronic channel. However, the specific heat from electronic term is only a fraction of lattice specific heat in YBa 2 Cu 3 O 7-δ high-Tc superconductors.