Significance of the Cu-O chain and a percolation model for superconductivity inYBa2Cu3O7−δ

Abstract

Percolative superconductivity observed in oxygen-deficient $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ is well understood in terms of inhomogeneous superconductivity in a homogeneous solid-solution phase, using a percolation model of a two-dimensional square lattice. The inhomogeneity is considered to be related to the very short coherence length of 20-30 Å in this material. It is also concluded that the very local oxygen ordering on the Cu(1) plane is significant for superconductivity.