Influence of surface morphology on the thickness dependence of high- Jc Sm 1+ xBa 2− xCu 3O 6+ δ films

Abstract

We have investigated a dependence of critical current density ( J c) on the thickness of Sm 1+ x Ba 2− x Cu 3O 6+ δ (SmBCO) films grown by pulsed laser deposition using x=0, 0.04 and 0.08 targets. Different behaviors were observed in the film thickness dependence of J c of x=0, 0.04 and 0.08 SmBCO films. The J c of x=0 and 0.04 SmBCO films decreased with increasing film thickness up to about 1 μm. In the region of the thickness over 1 μm, the x=0 and 0.04 SmBCO films maintained high- J c and the highest critical current ( I c *) calculated for 1 cm-width of about 520 A/cm-width was obtained at a film thickness of 2.1 μm for x=0.04 film. On the other hand, the J c of x=0.08 SmBCO film increased up to the film thickness of 1.1 μm and I c * reached a high value of about 480 A/cm-width. However, in the region of the thickness over 1.1 μm, the J c of x=0.08 film rapidly decreased. In this paper, we discuss how the difference of the precipitates affects the film thickness dependence of J c. From the SEM and TEM observation of the film, we found the precipitates of x=0 and 0.08 films as BaCuO compounds and crystallized Cu 2O, respectively. It is considered that the difference of the precipitates affects the film thickness dependence of J c.