Critical-current variation with Pr content in Y1-xPrxBa2Cu3O7 epitaxial films.

Abstract

c-axis-oriented epitaxial ${\mathrm{Y}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ (x=0, 0.05, 0.1, 0.2, 0.3, and 0.35) thin films have been grown with the pulsed-laser-deposition method. Superconducting transition temperatures of the films are within \ifmmode\pm\else\textpm\fi{}2 K of the corresponding polycrystalline bulk samples. The critical current density ${\mathit{J}}_{\mathit{c}}$ of Pr-doped films for x=0.1--0.3 is about two orders of magnitude lower than of the pure 1:2:3 films. This exponential fall in ${\mathit{J}}_{\mathit{c}}$ with doping (x) can be understood semiquantitatively in terms of depairing due to a random-impurity (Pr-ion) potential causing localized suppression of the superconducting order parameter around the impurity to about the in-plane coherence length.