paper

Enhancement of the superconducting critical temperature in Bi $_{2}$ Sr $_{2}$ CaCu $_{2}$ O $_{8 + I^´}$ by controlling disorder outside CuO $_{2}$ planes

arXiv:0904.2613 · doi:10.1103/PhysRevB.79.064507

Abstract

We investigate the effect of disorder at various lattice sites outside the CuO $_{2}$ plane on the superconducting critical temperature $T_{c}$ of the cuprate superconductor Bi $_{2}$ Sr $_{2}$ CaCu $_{2}$ O $_{8 + I^´}$ (Bi2212). The most effective disorder turns out to be that at the Sr site in the neighboring blocks, which contain apical-oxygen atoms. The Sr-site disorder reduces $T_{c}$ and also produces a residual component ( $I ¨ _{0}$ ) in the in-plane resistivity, the magnitude of which is found to be proportional to the magnitude of $T_{c}$ reduction. We demonstrate that both $T_{c}$ -degradation rate and $I ¨ _{0}$ decrease as the number of the CuO $_{2}$ planes increases in the unit cell, that is, as the number of the neighboring SrO blocks decreases. In real crystals of Bi-based cuprates, main source of disorder is Bi atoms randomly occupying the Sr sites. We have succeeded in reducing the Bi content at Sr-sites as much as possible and achieved $T_{c}$ =98K, a high- $T_{c}$ record in Bi2212.

7 pages, 1 table, 5 figures

Enhancement of the superconducting critical temperature in Bi2​Sr2​CaCu2​O8+I^´​ by controlling disorder outside CuO2​ planes

Abstract

Enhancement of the superconducting critical temperature in Bi $_{2}$ Sr $_{2}$ CaCu $_{2}$ O $_{8 + I^´}$ by controlling disorder outside CuO $_{2}$ planes