Letter abstract


Nature Physics 4, 550 - 554 (2008)
Published online: 22 June 2008 | doi:10.1038/nphys1000

Subject Categories: Statistical physics, thermodynamics and nonlinear dynamics | Condensed-matter physics | Materials physics

Unexpected drop of dynamical heterogeneities in colloidal suspensions approaching the jamming transition

Pierre Ballesta1,2, Agnès Duri1,2 & Luca Cipelletti1

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In supercooled molecular fluids or concentrated colloids and grains, the dynamics slow down markedly with no distinct structural changes as the glass1 or the jamming2 transition is approached. There is now ample evidence that structural relaxation in glassy systems can only occur through correlated rearrangements of particle 'blobs' of size xi (refs 3, 4, 5, 6, 7), leading to dynamics that are heterogeneous both in time and in space. On approaching these transitions, xi grows in glass-formers6, 7, 8, colloids3, 4, 9 and driven granular materials10 alike, strengthening the analogies between the glass and the jamming transitions and providing a possible explanation for the slowing down of the dynamics. However, little is known yet on the behaviour of dynamical heterogeneity very close to dynamical arrest. Here, we measure in colloids the maximum of a 'dynamical susceptibility', chi*, that quantifies the temporal fluctuations of the dynamics, the growth of which is usually associated with that of xi (ref. 11). We find that chi* initially increases with particle volume fraction, but drops markedly very close to jamming. We show that this behaviour results from the competition between the growth of xi and the reduced particle displacements associated with rearrangements in very dense suspensions, unveiling a richer-than-expected scenario.

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  1. LCVN UMR 5587, Université Montpellier 2 and CNRS, 34095 Montpellier Cedex 5, France
  2. Present Address: School of Physics, The University of Edinburgh, Edinburgh EH9 3JZ, UK (P.B.); HASYLAB at DESY, D-22603 Hambourg, Germany (A.D.)

Correspondence to: Luca Cipelletti1 e-mail: lucacip@lcvn.univ-montp2.fr



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