Analyzing Intrinsic Superconducting Gap by Means of Measurement of Bi-2212 Superconductors

TL;DR

This paper introduces a method to measure the intrinsic superconducting gap in Bi-2212 superconductors, accounting for inhomogeneity and band filling effects, revealing s-wave symmetry and gap anisotropy origins.

Contribution

It develops a new approach to extract the intrinsic gap and pairing symmetry in inhomogeneous high-Tc superconductors from conductance data.

Findings

Intrinsic gap GAP_i <= 10 meV measured at nodes.

Superconducting gap ratio b < 4 indicating s-wave symmetry.

Gap anisotropy linked to inhomogeneity of phases.

Abstract

For the mechanism of high-Tc superconductivity in inhomogeneous Bi-2212 superconductors, we demonstrate the intrinsic superconducting gap,GAP_i, and pairing symmetry by using a developed GAP=GAP_i/rho, where GAP is the observed energy gap and 0<rho<=1 is band filling. When rho=1, GAP=GAP_i<=10 meV, measured at a node, is intrinsic. When 0<rho<1, GAP implies an averaging of GAP_i over the measurement region, which is the effect of measurement. From analysis's of conductance data, b=2GAP_i/k_BT_c is less than 4 when rho=1 and the density of state indicates s-wave symmetry. The superconducting gap anisotropy is attributed to the inhomogeneity of the metal phase and the insulating d-wave phase in the measurement region.