J. Phys. I France 5 (1995) 517-524
Calculated Superconducting Gap Dependence on Doping in Single Layered Copper OxidesT. 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)
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.
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