Structure-dynamics relationship in ratcheted colloids: Resonance melting, dislocations, and defect clusters

Abstract

We consider a two dimensional colloidal dispersion of soft-core particles driven by a one dimensional stochastic flashing ratchet that induces a time averaged directed particle current through the system. It undergoes a non-equilibrium melting transition as the directed current approaches a maximum associated with a resonance of the ratcheting frequency with the relaxation frequency of the system. We use extensive molecular dynamics simulations to present a detailed phase diagram in the ratcheting rate-mean density plane. With the help of numerically calculated structure factor, solid and hexatic order parameters, and pair correlation functions, we show that the non-equilibrium melting is a continuous transition from a quasi-long ranged ordered solid to a hexatic phase. The transition is mediated by the unbinding of dislocations, and formation of compact and string-like defect clusters.

12 pages, 14 figures

References in corpus (11)

• Artificial Brownian motors: Controlling transport on the nanoscale
• 2D Melting: From Liquid-Hexatic Coexistence to Continuous Transitions
• Depinning and nonequilibrium dynamic phases of particle assemblies driven over random and ordered substrates: a review
• Realization of a feedback controlled flashing ratchet
• Reversible Vortex Ratchet Effects and Ordering in Superconductors with Simple Asymmetric Potential Arrays
• Driving particle current through narrow channels using classical pump
• Depinning dynamics of two-dimensional dusty plasmas on a one-dimensional periodic substrate
• Collective shuttling of attracting particles in asymmetric narrow channels
• Stochastic pump of interacting particles
• Pumping single-file colloids: Absence of current reversal
• Particle current in symmetric exclusion process with time-dependent hopping rates