Calculated Superconducting Gap Dependence on Doping in Single Layered Copper Oxides

T. Hocquet; J.-P. Jardin; P. Germain; J. Labbé

doi:doi:10.1051/jp1:1995144

Issue		J. Phys. I France Volume 5, Number 4, April 1995


Page(s)		517 - 524
DOI		https://doi.org/10.1051/jp1:1995144

DOI: 10.1051/jp1:1995144
J. Phys. I France 5 (1995) 517-524

Calculated Superconducting Gap Dependence on Doping in Single Layered Copper Oxides

T. Hocquet¹, J.-P. Jardin², P. Germain¹ and J. Labbé¹

¹ Laboratoire de Physique de la Matière Condensée de l'Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France
² Laboratoire PMTM (CNRS), Université Paris Nord, 93430 Villetaneuse, France

(Received 21 September 1994, received in final form 13 December 1994, accepted 15 December 1994)

Abstract
We use a total Hamiltonian containing both an electron-phonon induced attractive part of the interaction between electrons, and a Coulomb repulsive part formulated in the Hubbard model. By diagonalising it in the Bogoliubov and Valatin mean field approximation, we obtain equations for a two valued superconducting gap function, with a much more precise statement about the repulsive cut off energy than in the Mortel and Anderson model. By applying these equations to our bidimensional electronic model for a CuO ₂ plane, we find that the calculated superconducting gap decreases very slowly with increasing doping x in La _2-xSr _xCuO ₄, and we compare to the behaviour of the antiferromagnetic gap.