Dilute Co-doping effects on critical current properties in PLD-ErBa2Cu3Oy films

Abstract

We report the effects of dilute Co-doping on superconducting and critical current properties in ErBa2Cu3Oy/SrTiO3 (Er123/STO) thin films fabricated by pulsed laser deposition (PLD). Critical temperatures (Tc) were systematically increased with substrate temperature (Ts), and therefore the substitution levels of Co into the CuO2 planes can be controlled by Ts. On the other hand, the critical current density (Jc) increased with the decrease in Ts at low temperatures below 50K. The angular dependence of Jc for the films with relatively heavier Co-doping levels showed the c-axis peaks, which is quite contrast to that for the pure Er123 film. This behavior was observed not only at low temperatures but also at high temperatures. These results indicate that the Co-doping induced generation of the c-axis correlated vortex pinning centers in the Er123 matrix and this new type of pinning center is probably due to the existence of inhomogeneous distribution of the Co-doping levels in the films.