Superfluid density dominated junction resistance of bulk polycrystalline YBa2Cu3O7−δ and DyBa2Cu3O7−δ superconductors at low temperature

Abstract

Resistances of grain junctions of bulk polycrystalline YBa₂Cu₃O_7−δ (YBCO) and DyBa₂Cu₃O_7−δ (DyBCO) superconductors have been extracted following (i) Ambegaokar- Baratoff (AB) and (ii) de Gennes (dG) equations. Current–voltage (IV) below the critical temperature ($T_c$) has been used to extract transport critical current density ($J_c$). The variations of the junction resistances, ($R_N$) with temperature (T) exhibit that below a critical value of the normalised superfluid density (NSD), junctions become very low resistive and exhibit metallicity. Dependence of this feature of $R_N$ on the energy gaps has also been explored. Weak scattering limit is found to be compatible with the maximum of $R_N$ (T) as is observed from the corresponding NSD.