paper

A Theory for High- Superconductors Considering Inhomogeneous Charge Distribution

arXiv:cond-mat/0110519 · doi:10.1103/PhysRevB.67.024502

Abstract

We propose a general theory for the critical and pseudogap temperature dependence on the doping concentration for high- oxides, taking into account the charge inhomogeneities in the planes. The well measured experimental inhomogeneous charge density in a given compound is assumed to produce a spatial distribution of local . These differences in the local charge concentration is assumed to yield insulator and metallic regions, possibly in a stripe morphology. In the metallic region, the inhomogeneous charge density yields also spatial distributions of superconducting critical temperatures and zero temperature gap . For a given sample, the measured onset of vanishing gap temperature is identified as the pseudogap temperature, that is, , which is the maximum of all . Below , due to the distribution of 's, there are some superconducting regions surrounded by insulator or metallic medium. The transition to a superconducting state corresponds to the percolation threshold among the superconducting regions with different 's. To model the charge inhomogeneities we use a double branched Poisson-Gaussian distribution. To make definite calculations and compare with the experimental results, we derive phase diagrams for the BSCO, LSCO and YBCO families, with a mean field theory for superconductivity using an extended Hubbard Hamiltonian. We show also that this novel approach provides new insights on several experimental features of high- oxides.

7 pages, 5 eps figures, corrected typos

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