Ratio 2Δ0/kTc in a van Hove superconductor

Abstract

The influence of logarithmic singularity in the density of states at the Fermi energy on the zero-temperature gap-to-Tc ratio (R) of a high-temperature superconductor is studied within the framework of the BCS theory. An exact gap-ratio integral is derived. The numerical values for R are found to contradict the recent approximate results of Getino et al. [Phys. Rev. B 48, 597 (1993)]. © 1996 Plenum Publishing Corporation.