Off equilibrium fluctuations in a polymer glass

Buisson, L.; Ciliberto, S.

doi:10.1016/j.physd.2005.03.003

Cited by 9 publications

(8 citation statements)

References 37 publications

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“…In this article, we have reported the first computational measurements of the FDR for rotational degrees of freedom in a molecular liquid. We note in passing that previous experimental studies of the FDT violation were built on the observation of rotational dynamics, based on depolarized light-scattering or dielectric spectroscopy [30][31][32][33]. The evaluation of T ef f at different elongations, highlighted a rich and unexpected scenario.…”

Section: Discussionmentioning

confidence: 91%

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Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids

Ninarello

Gnan

Sciortino

2014

The Journal of Chemical Physics

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We discuss the observable-dependence of the effective temperature Teff, defined via the fluctuation-dissipation relation, of an out-of-equilibrium system composed by homonuclear dumbbell molecules. Teff is calculated by evaluating the fluctuation and the response for two observables associated, respectively, to translational and to rotational degrees of freedom, following a sudden temperature quench. We repeat our calculations for different dumbbell elongations ζ. At high elongations (ζ > 0.4), we find the same Teff for the two observables. At low elongations (ζ ⩽ 0.4), only for very deep quenches Teff coincides. The observable-dependence of Teff for low elongations and shallow quenches stresses the importance of a strong coupling between orientational and translational variables for a consistent definition of the effective temperature in glassy systems.

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Section: Discussionmentioning

confidence: 91%

“…However such result is limited to a single system and all the observables employed in the study are related to translational degrees of freedom. At odd, the scarce experimental works have focused on molecular glasses [30][31][32][33] and related to the observation of fluctuations and responses of molecules orientation.…”

Section: Introductionmentioning

confidence: 99%

Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids

Ninarello

Gnan

Sciortino

2014

The Journal of Chemical Physics

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“…Here, t obs ∼ 1 s is rather short compared to t w ∼ 10 3 s, corresponding to t obs /t w ∼ 10 −3 . Violations of FDT have been observed experimentally for very low values of t obs /t w : 10 −7 -10 −4 in a molecular glass [8], 10 −5 -10 −3 in polymer glasses [13,14], and 10 −7 -10 −4 in colloidal glasses [9,12,20]. Furthermore in those experimental systems, T eff does not rapidly approach the bath temperature T with waiting time t w .…”

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confidence: 99%

Experimental Evidence for Violation of the Fluctuation-Dissipation Theorem in a Superspin Glass

et al. 2011

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We present the experimental observation of the fluctuation-dissipation theorem violation in an assembly of interacting magnetic nanoparticles in the low temperature superspin-glass phase. The magnetic noise is measured with a two-dimension electron gas Hall probe and compared to the out of phase ac susceptibility of the same ferrofluid. For "intermediate" aging times of the order of 1 h, the ratio of the effective temperature T(eff) to the bath temperature T grows from 1 to 6.5 when T is lowered from T(g) to 0.3 T(g), regardless of the noise frequency. These values are comparable to those measured in an atomic spin glass as well as those calculated for a Heisenberg spin glass.

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“…In our experiment polycarbonate is used as the dielectric of a capacitor. The capacitor is composed by 14 cylindrical capacitors in parallel in order to reduce the resistance of the sample and to increase its capacity [20]. Each capacitor is made of two aluminum electrodes, 12µm thick, and by a disk of polycarbonate of diameter 12cm and thickness 125µm.…”

Section: Methodsmentioning

confidence: 99%

“…The electrical impedance of the capacitor is Z(ω, t w ) = R/(1 + iω R C), where C is the capacitance and R is a parallel resistance which accounts for the complex dielectric susceptibility. This is measured by a lock-in amplifier associated with an impedance adapter [20]. The noise spectrum S Z (ω, t w ) of the impedance Z(ω, t w ) is:…”

Section: Methodsmentioning

confidence: 99%

Thermal Noise Properties of Two Aging Materials

Bellon¹,

Buisson²,

Ciccotti³

et al.

Jamming, Yielding, and Irreversible Deformation in Condensed Matter

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In this lecture we review several aspects of the thermal noise properties in two aging materials: a polymer and a colloidal glass. The measurements have been performed after a quench for the polymer and during the transition from a fluid-like to a solid-like state for the gel. Two kind of noise has been measured: the electrical noise and the mechanical noise. For both materials we have observed that the electric noise is characterized by a strong intermittency, which induces a large violation of the Fluctuation Dissipation Theorem (FDT) during the aging time, and may persist for several hours at low frequency. The statistics of these intermittent signals and their dependance on the quench speed for the polymer or on sample concentration for the gel are studied. The results are in a qualitative agreement with recent models of aging, that predict an intermittent dynamics. For the mechanical noise the results are unclear. In the polymer the mechanical thermal noise is still intermittent whereas for the gel the violation of FDT, if it exists, is extremely small.

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Off equilibrium fluctuations in a polymer glass

Cited by 9 publications

References 37 publications

Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids

Observable-dependence of the effective temperature in off-equilibrium diatomic molecular liquids

Experimental Evidence for Violation of the Fluctuation-Dissipation Theorem in a Superspin Glass

Thermal Noise Properties of Two Aging Materials

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