Explanation of small I_cR_n values observed in inhomogeneous superconductors

TL;DR

This paper extends the Ambegaokar-Baratoff theory to inhomogeneous high-Tc superconductors, explaining small I_cR_n values through band-filling effects and analyzing the intrinsic gap from experimental data.

Contribution

It introduces a band-filling dependent model for Josephson I_cR_n in inhomogeneous superconductors, clarifying observed small values and providing a method to estimate the intrinsic superconducting gap.

Findings

J_{obs}R_n = 1.57 * rho * Gap_i explains small I_cR_n values

Intrinsic gap in Bi-2212 estimated between 8.5 and 17 meV

D-wave components are absent in Bi-2212 crystals

Abstract

For an inhomogeneous high-Tc superconductor, band-filling dependence of Josephson I_cR_n product is deduced at T=0 K by means of measurement; this is an extension of the Ambegaokar - Baratoff (AB) theory based on the s-wave theory. The product is given by J_{obs}R_n ={1.57}{rho}{Gap_i}={rho}J_iR_n, where 0<{rho}<=1 is band filling (or local density), and {Gap_i} is the intrinsic superconducting true gap and small. When {rho}=1, J_{obs}R_n=J_iR_n is the intrinsic Josephson true product (or the AB product), where J_i is the intrinsic Josephson true current occurring by Cooper pair. When 0<{rho}<1, J_{obs}R_n is an average of J_iR_n over the measurement region and is the effect of measurement. The J_{obs}R_n explains small I_cR_n values observed by experiments. Furthermore, the intrinsic gap, 8.5<{Gap_i}<17 meV, is analyzed from I_cR_n data of Bi-2212. d-wave superconductive components do not exist in Bi-2212 crystals.