title: Heterogeneous dynamics and ageing in a dense ferro-glass.
abstract: Repulsive magnetic fluids show a dynamical freezing above a volume fraction Φ(*), which depends on the physico-chemistry of the system. Φ(*) is here determined by a magneto-optical technique. The out-of-equilibrium dynamics of a glass-forming magnetic fluid (Φ = 1.2Φ(*)) is studied by x-ray photon correlation spectroscopy and analyzed in terms of intensity auto-correlation functions. The relaxation is age dependent and follows a compressed exponential law with a characteristic time scaling as the inverse of the scattering vector Q. The dynamical susceptibility χ is then deduced from a time resolved correlation analysis at an intermediate Q and for ages larger than 10(4) s.
authors.affiliation: Université Pierre et Marie Curie-Paris 6, Laboratoire Liquides Ioniques et Interfaces Chargées (UMR 7612 UPMC/CNRS/ESPCI), 4, place Jussieu,-case 51, 75252 Paris Cedex 05, France.
authors.forename: E
authors.initials: E
authors.lastname: Wandersman
authors.forename: E
authors.initials: E
authors.lastname: Dubois
authors.forename: V
authors.initials: V
authors.lastname: Dupuis
authors.forename: A
authors.initials: A
authors.lastname: Duri
authors.forename: A
authors.initials: A
authors.lastname: Robert
authors.forename: R
authors.initials: R
authors.lastname: Perzynski