Brownian dynamics study of driven partially pinned solid in the presence of square array of pinning centers: Enhanced pinning close to the melting transition

TL;DR

This study uses Brownian dynamics simulations to analyze how driven vortex lattices with partial pinning behave near melting, revealing a non-monotonic velocity-temperature relationship similar to the peak effect.

Contribution

It provides new insights into the temperature-dependent depinning behavior of partially pinned vortex lattices, highlighting the peak effect near melting.

Findings

Average vortex velocity shows a minimum near melting temperature.

Non-monotonic velocity behavior with temperature in driven vortex systems.

Energy barrier calculations support increased barriers near melting.

Abstract

A set of interacting vortices in $2D$ in the presence of a substrate with square symmetry and at filling ratio $1$ can display a low temperature solid phase where only one of the reciprocal lattice vectors of the substrate is present\cite{toby1,fasano}. This partially pinned vortex lattice melts to a modulated liquid via a continuous transition \cite{toby1}. Brownian dynamics simulation is carried out to study the behavior of driven partially pinned solid at different temperatures. The average vortex velocity for forces above the depinning threshold shows a non-monotonic behavior with temperature, with a minimum in the average velocity close to the melting point. This is reminiscent of the peak effect seen in vortex systems with random disorder. This effect in the current system can be qualitatively explained by an effective increase in the barriers encountered by the particles as $T_c$ is approached. Approximate calculation of the energy barriers as a function of temperature, from the simulation supports this claim.