title: Order-disorder transitions in a sheared many-body system.
abstract: Motivated by experiments on sheared suspensions that show a transition between ordered and disordered phases, we here study the long-time behavior of a sheared and overdamped two-dimensional system of particles interacting by repulsive forces. As a function of interaction strength and shear rate we find transitions between phases with vanishing and large single-particle diffusion. In the phases with vanishing single-particle diffusion, the system evolves towards regular lattices, usually on very slow time scales. Different lattices can be approached, depending on interaction strength and forcing amplitude. The disordered state appears in parameter regions where the regular lattices are unstable. Correlation functions between the particles reveal the formation of shear bands. In contrast to single-particle densities, the spatially resolved two-particle correlation functions vary with time and allow to determine the phase within a period. As in the case of the suspensions, motion in the state with low diffusivity is essentially reversible, whereas in the state with strong diffusion it is not.
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany.
authors.forename: Jens C
authors.initials: JC
authors.lastname: Pfeifer
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125,USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Bischoff
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Ehlers
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany.
authors.forename: Bruno
authors.initials: B
authors.lastname: Eckhardt