Studies on Isotope Shift Exponent and Pressure Coefficient for Extended Superconductors within BCS Formalism
B. Banerjee and S.K. Roy
Department of Physics, Visva-Bharati University, Santiniketan - 731 235, India
Received: March 5, 2008; Revised version: September 2, 2008
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A tight-binding model comprising a hopping and an attractive interaction term was considered for high temperature superconductors. Explicit calculations on the effects of isotopic substitution of atoms and application of pressure on the transition temperatures were made in this work. Exact analytical expressions for the isotope-shift exponent (α) and pressure coefficient (γP ) of transition temperature (TC) considering the isotopic mass and pressure dependence of the hopping and attractive interaction strengths from a minimal model describing superconductivity were obtained. Theoretical predictions for α and γP with proper choice of parameters are found to be qualitatively consistent with the results of the experiments of high TC oxides. The results depend on the band dispersion chosen.
DOI: 10.12693/APhysPolA.115.914
PACS numbers: 74.20+f, 74.25.Bt, 74.25.Ha