Growth and superconducting transition of $Pr_{1-x} Ca_x Ba_2 Cu_3 O_{7-\delta}$ ($x\approx0.5$) epitaxial thin films

TL;DR

This study investigates the growth, orientation, and superconducting properties of Pr$_{1-x}$Ca$_x$Ba$_2$Cu$_3$O$_{7-eta}$ thin films on different substrates, revealing optimal conditions for high transition temperatures and insights into their electronic scattering behaviors.

Contribution

It systematically analyzes substrate temperature effects on film orientation and superconductivity, providing new insights into optimizing growth conditions for these cuprate thin films.

Findings

Highest $T_{C0}$ of about 37K on YSZ with c-axis orientation

Good quality films can be grown with controlled orientation on different substrates

Weak temperature dependence of resistivity suggests localized electronic states

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 $R(290K)/R(50K)\leq2$ 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 $B^{ab}_{C2}$(0) is estimated from the resistivity transition data.