On the broadening of low dimension van Hove singularities in oxide superconductors
- 1 January 1988
- journal article
- Published by EDP Sciences in Journal de Physique
- Vol. 49 (8) , 1435-1441
- https://doi.org/10.1051/jphys:019880049080143500
Abstract
It is pointed out that the transverse couplings and, accessorily, the longitudinal scattering by doping and phonons broaden enough the 2d van Hove singularities of Cu O2 planes to prevent their spontaneous Jahn Teller splitting. The tetragonal-orthorhombic phase changes observed in La2-x Sr x Cu O4-y and Y Ba2 Cu3 O7 -δ have then different origins and nature. In good crystals, this broadening is not sufficient to destroy the antiferromagnetic or superconductive instabilities, contrary to the scattering by vacancies along the 1d Cu O chains in understœchiometric Y Ba2 Cu 3 O7-δ. A previous analysis of superconductivity, starting from quasilowdimensionality and weak coupling, is revised to take this broadening into accountKeywords
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