Growth and superconducting transition of $P{r}_{1-x}C{a}_{x}B{a}_{2}C{u}_3{O}_{7-\delta }$ ($x\approx 0.5$) epitaxial thin films

Abstract

Pr${}_{1-x}$Ca${}_x$Ba${}_2$Cu${}_3$O${}_{7-\delta }$($x\approx$0.5) thin films have been grown on SrTiO${}_3$ and YSZ substrates by the pulsed laser ablation. The substrate temperature dependence of orientation and superconducting poperties were systematically studied. Good quality \textit{c} and {a}-axis orientated films can be obtained on SrTiO${}_3$ via changing the substrate temperature solely. On YSZ, films with good \textit{c}-axis orientation can be grown, while it is hard to grow films with good \emph{a}-axis orientation by changing substrate temperature alone. The highest $T_{C0}$ is about 37K, which is found in the films grown on YSZ with a good \emph{c}-axis orientation. For the films grown on STO, however, the highest $T_{C0}$ is about 35.6K with a mixed orientation of \emph{c}-axis and \emph{a}-axis. In most of the superconducting films, the weak temperature dependence of the normal state resistivity, as characterized by small $R(290K)/R(50K)\le 2$ ratios, together with a weak localization behavior just above $T_C$ could be attributed to the essential scattering due to the localized electronic states. The superconducting transitions in a field up to 10 T along \textit{c}-axis have been measured on a \textit{c}-axis oriented film grown on SrTiO${}_3$. The zero-temperature in-plane upper critical field $B_{C2}^{ab}$(0) is estimated from the resistivity transition data.

12 pages, 5 figures. To be appear in Supercond. Sci. Technol. 17 (2004)