Moving Vortex Phases, Dynamical Symmetry Breaking, and Jamming for Vortices in Honeycomb Pinning Arrays

TL;DR

This paper uses numerical simulations to explore complex vortex behaviors in honeycomb pinning arrays, revealing novel dynamical phases, symmetry breaking, and jamming phenomena that differ from other lattice geometries.

Contribution

It introduces the concept of vortex molecular crystals and demonstrates how dimer states lead to unique dynamical phases and jamming effects in honeycomb arrays.

Findings

Dimer states cause dynamical symmetry breaking and transverse transport.

Reorientation of dimers induces jamming and increases depinning force.

Jamming effects can be enhanced by reducing pinning site size.

Abstract

We show using numerical simulations that vortices in honeycomb pinning arrays can exhibit a remarkable variety of dynamical phases that are distinct from those found for triangular and square pinning arrays. In the honeycomb arrays, it is possible for the interstitial vortices to form dimer or higher n-mer states which have an additional orientational degree of freedom that can lead to the formation of vortex molecular crystals. For filling fractions where dimer states appear, a novel dynamical symmetry breaking can occur when the dimers flow in one of two possible alignment directions. This leads to transport in the direction transverse to the applied drive. We show that dimerization produces distinct types of moving phases which depend on the direction of the driving force with respect to the pinning lattice symmetry. When the dimers are driven along certain directions, a reorientation of the dimers can produce a jamming phenomenon which results in a strong enhancement in the critical depinning force. The jamming can also cause unusual effects such as an increase in the critical depinning force when the size of the pinning sites is reduced.