Eur. Phys. J. B 23, 159-163 (2001)
https://doi.org/10.1007/s100510170063

A simple theory for high Δ/Tc ratio in d-wave superconductors

Laboratoire de Physique Statistique, École Normale Supérieure (Laboratoire associé au Centre National de la Recherche Scientifique et aux Universités Paris 6 et Paris 7) , 24 rue Lhomond, 75231 Paris Cedex 05, France

Corresponding author: ^a combesco@physique.ens.fr

Received: 12 March 2001
Revised: 25 May 2001
Published online: 15 September 2001

Abstract

We investigate a simple explanation for the high maximum gap to T_c ratio found experimentally in high T_c compounds. We ascribe this observation to the lowering of T_c by boson scattering of electrons between parts of the Fermi surface with opposite sign for the order parameter. We study the simplest possible model within this picture. Our quantitative results show that we can account for experiment for a rather small value of the coupling constant, all the other ingredients of our model being already known to exist in these compounds. A striking implication of this theory is the fairly high value of the critical temperature in the absence of boson scattering.