Vortex Shear Banding Transitions in Superconductors with Inhomogeneous Pinning Arrays

TL;DR

This study numerically investigates vortex flow and shear banding transitions in superconductors with inhomogeneous pinning arrays, revealing stepwise depinning and flow immobilization phenomena.

Contribution

It introduces a detailed numerical analysis of vortex shear banding transitions in superconductors with inhomogeneous pinning, highlighting new depinning behaviors and flow control mechanisms.

Findings

Shear bands initiate in pin-free channels during depinning.

Velocity-force curves exhibit jumps corresponding to shear band depinning.

Flow can be completely immobilized, demonstrating a field effect transistor behavior.

Abstract

We numerically examine the flow of superconducting vortices in samples containing square pinning arrays in which a band of pins is removed. When a drive is applied at an angle with respect to the band orientation, we find that the vortex depinning initiates in the pin-free channel. The moving vortices form a series of quasi-one-dimensional shear bands that begin flowing in the bulk of the pin-free channel, and the motion gradually approaches the edge of the pinned region. The consecutive depinning of each shear band appears as a series of jumps in the velocity-force curves and as sharp steps in the spatial velocity profiles. When a constant drive is applied parallel to the pin-free channel along with a gradually increasing perpendicular drive, the net vortex velocity decreases in a series of steps that correspond to the immobilization of bands of vortices, and in some cases the flow can drop to zero, creating a field effect transistor phenomenon. These results should also be relevant to other types of systems that exhibit depinning in the presence of inhomogeneous pinning.