title: Divergence of the third harmonic stress response to oscillatory strain approaching the glass transition.
abstract: The leading nonlinear stress response in a periodically strained concentrated colloidal dispersion is studied experimentally and by theory. A thermosensitive microgel dispersion serves as well-characterized glass-forming model, where the stress response at the first higher harmonic frequency (3ω for strain at frequency ω) is investigated in the limit of small amplitude. The intrinsic nonlinearity at the third harmonic exhibits a scaling behavior which has a maximum in an intermediate frequency window and diverges when approaching the glass transition. It captures the (in-) stability of the transient elastic structure. Elastic stresses in-phase with the third power of the strain dominate the scaling. Our results qualitatively differ from previously derived scaling behavior in dielectric spectroscopy of supercooled molecular liquids. This might indicate a dependence of the nonlinear response on the symmetry of the external driving under time reversal.
authors.affiliation: Department of Physics, Universität Konstanz, 78464 Konstanz, Germany. matthias.fuchs@uni-konstanz.de and Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany.
authors.forename: Rabea
authors.initials: R
authors.lastname: Seyboldt
authors.affiliation: Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Merger
authors.affiliation: Department of Physics, Universität Konstanz, 78464 Konstanz, Germany. matthias.fuchs@uni-konstanz.de.
authors.forename: Fabian
authors.initials: F
authors.lastname: Coupette
authors.affiliation: Institute Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Siebenbürger
authors.affiliation: Institute Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Ballauff
authors.affiliation: Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Wilhelm
authors.affiliation: Department of Physics, Universität Konstanz, 78464 Konstanz, Germany. matthias.fuchs@uni-konstanz.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Fuchs