Lane formation in colloidal mixtures driven by an external field

Abstract

The influence of an external field on a binary colloidal mixture performing Brownian dynamics in a solvent is investigated by nonequilibrium computer simulations and simple theory. In our model, one half of the particles are pushed into the field direction while the other half of them are pulled into the opposite direction. For increasing field strength, we show that the system undergoes a nonequilibrium phase transition from a disordered state to a state characterized by lane formation parallel to the field direction. The lanes are formed by the same kind of particles moving collectively with the field. Lane formation accelerates particle transport parallel to the field direction but suppresses massively transport perpendicular to the field. We further show that lane formation also occurs in a time-dependent oscillatory field. If the frequency of the external field exceeds a critical value, however, the system exhibits a transition back to the disordered state. Our results can be experimentally verified in binary colloidal suspensions exposed to external fields under nonequilibrium conditions.

Shear-induced laning transition in a confined colloidal film

“…From a physical point of view the occurrence of the lanes is maybe not surprising: We recall that, in the present shear geometry, particles at equal distance from the middle plane experience an oppositely directed shear force via the externally controlled flow profile. The occurence of a "laning transition" in binary systems of oppositely driven particles is indeed a well-established phenomenon which has been observed in a wide variety of systems including colloids and pedestrians [34,41]. Inspired by the numerous studies of laning in colloidal systems we here define a laning order parameter (see, e.g., [41]) addressing the particles in the middle layer.…”

“…The occurence of a "laning transition" in binary systems of oppositely driven particles is indeed a well-established phenomenon which has been observed in a wide variety of systems including colloids and pedestrians [34,41]. Inspired by the numerous studies of laning in colloidal systems we here define a laning order parameter (see, e.g., [41]) addressing the particles in the middle layer. We first assign to each particle the parameter φ i , which is chosen to be 1 if the lateral distance |y i − y j | to all particles of the adjacent sublayer j is larger than the average distance r lane = ρ −1/3 /2.…”

Binary crystals in two-dimensional two-component Yukawa mixtures

“…Likewise the pure (one-component) Yukawa system was also studied in two-spatial dimensions for fluid structure [21,22,23,24], dynamics [25,26,27,28] and transport properties [29]. Binary mixtures of Yukawa particles in two dimensions have also been studied for fluid structure [30], adsorption [31], interfaces [32] and transport [33]. However, the crystallization issue was only addressed in one-component Yukawa systems (for a recent work, see e.g.…”

Nonequilibrium anisotropic phases, nucleation, and critical behavior in a driven Lennard-Jones fluid

“…This occurs during segregation in driven sheared systems 5,6,7 , flowing fluids 8 , shaken granular matter 9,10 , and non-equilibrium liquid-liquid binary mixtures 11 , and it has been reproduced in computer simulations of driven colloidal 12 and fluid 4,13 systems, for instance. Further examples are the anisotropies observed in both high-temperature superconductors 14,15 and electron gases 16,17 .…”