Novel structure formation of a phase separating colloidal fluid in a ratchet potential
Institute of Theoretical Physics, Secr. EW 7-1, Technical University Berlin - Hardenbergstr. 36, D-10623 Berlin, Germany
Received: 13 March 2014
Accepted: 19 May 2014
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.
PACS: 64.75.Xc – Phase separation and segregation in colloidal systems / 47.54.-r – Pattern selection; pattern formation / 64.70.Nd – Structural transitions in nanoscale materials
© EPLA, 2014