Vortex deformation and breaking in superconductors: A microscopic description

TL;DR

This paper presents a microscopic elastic model for vortex deformation and breaking in layered superconductors with high and low pinning regions, explaining experimental observations and extracting intrinsic vortex parameters.

Contribution

The authors develop a new elastic model for vortex deformation in layered superconductors, applicable to various experimental configurations, and extract intrinsic vortex parameters from experimental data.

Findings

Vortex breaks when current exceeds a critical value, causing finite resistance.

Model applies to YBCO grain boundaries and films on vicinal substrates.

Extracted vortex line tension matches theoretical predictions.

Abstract

Vortex breaking has been traditionally studied for nonuniform critical current densities, although it may also appear due to nonuniform pinning force distributions. In this article we study the case of a high-pinning/low-pinning/high-pinning layered structure. We have developed an elastic model for describing the deformation of a vortex in these systems in the presence of a uniform transport current density $J$ for any arbitrary orientation of the transport current and the magnetic field. If $J$ is above a certain critical value, $J_c$, the vortex breaks and a finite effective resistance appears. Our model can be applied to some experimental configurations where vortex breaking naturally exists. This is the case for YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) low angle grain boundaries and films on vicinal substrates, where the breaking is experienced by Abrikosov-Josephson vortices (AJV) and Josephson string vortices (SV), respectively. With our model, we have experimentally extracted some intrinsic parameters of the AJV and SV, such as the line tension $\epsilon_l$ and compared it to existing predictions based on the vortex structure.