Strong improvement of the transport characteristics of YBa$_\textrm{2}$Cu$_\textrm{3}$O$_\textrm{7-x}$ grain boundaries using ionic liquid gating

TL;DR

This study demonstrates that ionic liquid gating can significantly enhance the transport properties of YBa2Cu3O7-x grain boundaries, offering a new approach to improve the performance of cuprate superconductors.

Contribution

The paper introduces ionic liquid gating as an effective method to tune and improve the transport characteristics of low-angle grain boundaries in YBa2Cu3O7-x thin films.

Findings

Gating alters the IV characteristics of grain boundaries.

Large variation in local depairing current density with gating.

Potential routes to mitigate transport loss at grain boundaries.

Abstract

For more than 30 years, the remarkable superconducting properties of REBa$_\textrm{2}$Cu$_\textrm{3}$O$_\textrm{7-x}$ (RE = rare earth) compounds have triggered research studies across the world. Accordingly, significant progresses have been made both from a basic understanding and a fabrication processes perspective. Yet, today, the major technological bottleneck towards the spread of their practical uses remains the exponential decay of their critical current with grain misorientation in polycrystalline samples. In this work, we used an ionic liquid to apply extremely high transverse electric fields to YBa$_\textrm{2}$Cu$_\textrm{3}$O$_\textrm{7-x}$ thin films containing a single well-defined low-angle grain boundary. Our study shows that this technique is very effective to tune the IV characteristics of these weak-links. In-magnetic field measurements allow us to discuss the type of the vortices present at the grain boundary and to unveil a large variation of the local depairing current density with gating. Comparing our results with the ones obtained on chemically-doped grain boundaries, we discuss routes to evaluate the role of local strain in the loss of transparency at cuprates low-angle grain boundaries. In short, this study offers a new opportunity to discuss scenarios leading to the reduced transport capabilities of grain boundaries in cuprates.