title: Transition to a labyrinthine phase in a driven granular medium.
abstract: Labyrinthine patterns arise in two-dimensional physical systems submitted to competing interactions, in fields ranging from solid-state physics to hydrodynamics. For systems of interacting particles, labyrinthine and stripe phases were studied in the context of colloidal particles confined into a monolayer, both numerically by means of Monte Carlo simulations and experimentally using superparamagnetic particles. Here we report an experimental observation of a labyrinthine phase in an out-of-equilibrium system constituted of macroscopic particles. Once sufficiently magnetized, they organize into short chains of particles in contact and randomly orientated. We characterize the transition from a granular gas state towards a solid labyrinthine phase, as a function of the ratio of the interaction strength to the kinetic agitation. The spatial local structure is analyzed by means of accurate particle tracking. Moreover, we explain the formation of these chains using a simple model.
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, MSC, CNRS (UMR 7057), 75013 Paris, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Merminod
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, MSC, CNRS (UMR 7057), 75013 Paris, France.
authors.forename: Timothée
authors.initials: T
authors.lastname: Jamin
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, MSC, CNRS (UMR 7057), 75013 Paris, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Falcon
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, MSC, CNRS (UMR 7057), 75013 Paris, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Berhanu