Critical current of superconducting YBa2Cu3O7-delta films with different in-plane orientations

Abstract

By using a pulsed-laser deposition (PLD) technique, we grow high quality YBa2Cu3O7-delta films on YSZ (Yt-stabilized Zr) substrates with 0-degree and 45-degree in-plane orientations at 810 degrees C and 690 degrees C respectively. Surprisingly, despite the large difference in growth temperature the qualities of the films are almost the same. To study the subtle differences between these two types of films, we measured both the temperature and magnetic field dependencies of the critical current. Although there is very little difference in their magnetic field dependence, there is a distinct temperature dependence, i.e. J(c)(1 - T/T-c) proportional to (1 - T/T-c)(5/4) for 0 degree in-plane orientation and proportional to (1 - T/T-c)(3/2) for 45 degree in-plane orientation at temperatures near T-c. We also studied the critical current densities with different fractions of mixed orientations, and found an empirical formula J(c) proportional to e(5 alpha) where alpha is the fraction of the majority domain.