title: Dynamical clustering and phase separation in suspensions of self-propelled colloidal particles.
abstract: We study experimentally and numerically a (quasi-)two-dimensional colloidal suspension of self-propelled spherical particles. The particles are carbon-coated Janus particles, which are propelled due to diffusiophoresis in a near-critical water-lutidine mixture. At low densities, we find that the driving stabilizes small clusters. At higher densities, the suspension undergoes a phase separation into large clusters and a dilute gas phase. The same qualitative behavior is observed in simulations of a minimal model for repulsive self-propelled particles lacking any alignment interactions. The observed behavior is rationalized in terms of a dynamical instability due to the self-trapping of self-propelled particles.
authors.affiliation: II. Institut für Physik, Universität Stuttgart, D-70569 Stuttgart, Germany.
authors.forename: Ivo
authors.initials: I
authors.lastname: Buttinoni
authors.affiliation: Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Bialké
authors.affiliation: II. Institut für Physik, Universität Stuttgart, D-70569 Stuttgart, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Kümmel
authors.affiliation: Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Löwen
authors.affiliation: II. Institut für Physik, Universität Stuttgart, D-70569 Stuttgart, Germany and Max-Planck-Institute for Intelligent Systems, D-70569 Stuttgart, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Bechinger
authors.affiliation: Institut für Theoretische Physik II, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Speck