rencontredunonlin´eaire2010 Fusion bidimensionnelle d’un cristal de pics de ferrofluide
1 2 Franc¸oisBoyer&EricFalcon
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1 InstitutUniversitairedesSyste`mesThermiquesIndustriels(IUSTI),Universite´deProvence,CNRS(UMR 6595), 5 rue Enrico Fermi 13453 Marseille cedex 13, France 2 LaboratoireMati`ereetSyste`mesComplexes(MSC),Universite´ParisDiderot,CNRS(UMR7057),10rueA. Domon et L. Duquet 75013 Paris, France francois.boyer@polytech.univmrs.fr ;eric.falcon@univparisdiderot.fr
R´esume´.e(dinn´elidetesoenhpe)utsaeioatrvseobl’nstonese´rpsuoNordohaseunepntreoiensntitaardnle de´sordonne´e(diteliquide)d’unre´seaudepics`alasurfaced’unferrofluidesoumisa`desvibrationshorizon talessinusoı¨dales.Latransitiondefusionseproduitpourunde´placementcritiquedespicsdontonmontre exp´erimentalementqu’ilsuitlecrit`eredeLindemann,pourdeuxtopologiesdiffe´rentes(hexagonaleetcarre´e)et surunelargeplagedemaillesdure´seau.Unephaseinterme´diairehexatiqueentrelesphasessolideetliquideest e´galementobserv´eeetcaracte´rise´eparlesfonctionsdecorr´elation.Cesyste`medissipatifhors´equilibrepr´esente de fortes similitudes avec la fusion bidimensionnelle (2D) en physique des solides.
Abstract.We report the observation of the transition from an ordered solidlike phase to a disordered liquid like phase of a lattice of peaks on a ferrofluid surface submitted to horizontal sinusoidal vibrations. The melting transition occurs for a critical peak displacement which is experimentally found to follow the Lindemann criterion, for two different lattice topologies (hexagonal and square) and over a wide range of lattice wavelengths. An intermediate hexaticlike phase between the solid and isotropic liquid phases is also observed and characterized by the correlation functions. This dissipative outofequilibrium system exhibits strong similarities with 2D melting in solidstate physics.