Phase-Locking of Vortex Lattices Interacting with Periodic Pinning

TL;DR

This study investigates the phase-locking phenomena of vortex lattices in superconductors interacting with periodic pinning arrays, revealing how AC and DC currents induce Shapiro steps and how these are influenced by magnetic field strength and lattice symmetry.

Contribution

It provides experimental evidence of Shapiro steps in vortex lattices with periodic pinning and confirms the Bessel function dependence of phase-locked step widths, enhancing understanding of vortex dynamics.

Findings

Shapiro steps observed for specific magnetic fields

Step widths follow Bessel function dependence

Pronounced steps occur at high-symmetry lattice configurations

Abstract

We examine Shapiro steps for vortex lattices interacting with periodic pinning arrays driven by AC and DC currents. The vortex flow occurs by the motion of the interstitial vortices through the periodic potential generated by the vortices that remain pinned at the pinning sites. Shapiro steps are observed for fields B_{\phi} < B < 2.25B_{\phi} with the most pronouced steps occuring for fields where the interstitial vortex lattice has a high degree of symmetry. The widths of the phase-locked current steps as a function of the magnitude of the AC driving are found to follow a Bessel function in agreement with theory.