Current reversal in interacting colloids under time-periodic drive

TL;DR

This study uses molecular dynamics simulations to explore how interacting colloidal particles on a ring exhibit current reversal under different time-periodic driving protocols, revealing conditions for current direction change and scaling behaviors.

Contribution

It introduces a novel investigation of current reversal phenomena in colloids driven by time-periodic potentials with different protocols, highlighting the impact of discrete jumps.

Findings

Current always positive in uniform velocity drive

Current reverses direction with discrete jump drive under certain conditions

Scaling form for current as a function of system parameters

Abstract

Using molecular dynamics simulations, we study particle-transport in a system of interacting colloidal particles on a ring, where the system is driven by a time-dependent external potential, moving along the ring. We consider two driving protocols: (i) the external potential barrier moves with a uniform velocity $v$ along the ring, and (ii) it moves in discrete jumps with jump-length $l$ and waiting time $\tau$ with an effective velocity $v=l/\tau$. The time-averaged (dc) particle current, which always remains positive in case (i), interestingly reverses its direction in case (ii) upon tuning the particle-number density $\rho_0$ and the effective barrier velocity $v$. We also find a scaling form for the current in terms of number density, barrier velocity, barrier height and temperature of the system.