In-plane anisotropy of electrical transport in Y$_{0.85}$Tb$_{0.15}$Ba$_2$Cu$_3$O$_{7-x}$ films

TL;DR

This study investigates the in-plane electrical anisotropy of Y$_{0.85}$Tb$_{0.15}$Ba$_2$Cu$_3$O$_{7-x}$ films, revealing anisotropic superconducting and normal state properties, and explores their potential for fundamental research and device applications.

Contribution

It provides the first detailed analysis of in-plane anisotropy in terbium-doped YBCO films and links the anisotropic resistive transition to theoretical models like Tinkham's and BKT.

Findings

In-plane anisotropy observed in both superconducting and normal states.

Resistive transition anisotropy explained by Tinkham's and BKT models.

YTbBCO films are promising for BKT research and high kinetic inductance devices.

Abstract

We fabricate high-quality c-axis oriented epitaxial YBa$_2$Cu$_3$O$_{7-x}$ films with 15% of yttrium atoms replaced by terbium (YTBCO) and study their electrical properties. The Tb substitution reduces the charge carrier density resulting in increased resistivity and decreased critical current density compared to the pure YBa$_2$Cu$_3$O$_{7-x}$ films. The electrical properties of the YTBCO films show an in-plane anisotropy in both the superconducting and normal state providing evidence for the twin-free film. Unexpectedly, the resistive transition of the bridges also demonstrates the in-plane anisotropy that can be explained within the framework of Tinkham's model of the resistive transition and the Berezinskii-Kosterlitz-Thouless (BKT) model depending on the sample parameters. We consider YTBCO films to be a promising platform for both the fundamental research on the BKT transition in the cuprate superconductors and for the fabrication of devices with high kinetic inductance.