Novel structure formation of a phase separating colloidal fluid in a ratchet potential

Abstract

Based on Dynamical Density Functional Theory (DDFT) we investigate a binary mixture of interacting Brownian particles driven over a substrate via a one-dimensional ratchet potential. The particles are modeled as soft spheres where one component carries a classical Heisenberg spin. In the absence of a substrate field, the system undergoes a first-order fluid-fluid demixing transition driven by the spin-spin interaction. We demonstrate that the interplay between the intrinsic spinodal decomposition and time-dependent external forces leads to a novel dynamical instability where stripes against the symmetry of the external potential form. This structural transition is observed for a broad range of parameters related to the ratchet potential. Moreover, we find intriguing effects for the particle transport.

arXiv comment6 pages, 4 figures

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• Lane formation dynamics of oppositely self-driven binary particles: Effects of density and finite system size
• Freezing of a soft-core fluid in a one-dimensional potential: Predictions based on a pressure-balance equation