Thermodynamic properties of yttrium based cuprate due to electron-cooper pair interaction using BVT

Abstract

Since the discovery of high temperature superconductivity (HTSC), there have been varied results concerning the high pairing energy in the unconventional superconductivity. In an attempt to unearth the mechanism behind the high pairing energy, we study a model in which an excited electron interacts with a Cooper pair. The interaction was studied earlier on using second quantization which depended on a wave function. We now use Bogoliubov- Valatini transformation (BVT) that is independent of the wave function to study the thermodynamic properties due to the interaction between an electron and a Cooper pair in a Yttrium based cuprate. The interaction energy increases with temperature and at T = 93 K ; we record the interaction energy of 2.173 meV and the specific heat of 4.669 J∙mol−1∙K−1. The entropy of this system is found to be 5.11 mJ∙g−1∙K−1. The Sommerfeld’s coefficient is maximum at T = 2/3 Tc where γ = 62.4 mJ ⋅mol−1 ⋅K−2 . It has also been observed, for the first time, that the thermodynamic quantities of YBCO123 are constant when temperature varies between 0 K and 18 K. Above 18 K, the thermodynamic quantities rise sharply. This observation has been attributed to the pairing of electrons in the singlet-s and singlet-p states.