Possible relevance of lattice effects in high-T c superconductors

Abstract

The relevance of the lattice-mediated superconducting pairing in a system of quasilocalized polarons dressed by local lattice deformations is considered. The spin correlations are taken into account using thet-J model expressed in terms of holon and spin operators. The Holstein-like Hamiltonian for holons with the transport term depending on spin correlations is transformed by the generalized Lang-Firsov transformation which implies the spread of the charge and the deformations to the nearest neighbours. The analytical formula for the superconducting transition temperatureTc is deduced using the assumption of an extremely narrow polaron band. The hole-concentration dependence ofTc and the isotope exponent are discussed using the classical approximation for incommensurate spiral spin correlations.