title: Nonequilibrium two-phase coexistence in a confined granular layer.
abstract: We report the observation of the homogenous nucleation of crystals in a dense layer of steel spheres confined between two horizontal plates vibrated vertically. Above a critical vibration amplitude, two-layer crystals with square symmetry were found to coexist in steady state with a surrounding granular liquid. By analogy to equilibrium hard-sphere systems, the phase behavior may be explained through entropy maximization. However, dramatic nonequilibrium effects are present, including a significant difference in the granular temperatures of the two phases.
authors.affiliation: Department of Physics, Georgetown University, 37th & O Streets, Washington, DC 20057, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Prevost
authors.forename: Paul
authors.initials: P
authors.lastname: Melby
authors.forename: David A
authors.initials: DA
authors.lastname: Egolf
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Urbach