Evidence for marginal stability in emulsions

Jie Lin, Ivane Jorjadze, Lea Laetitia Pontani, Matthieu Wyart, Jasna Brujic

    Research output: Contribution to journalArticlepeer-review


    We report the first measurements of the effect of pressure on vibrational modes in emulsions, which serve as a model for soft frictionless spheres at zero temperature. As a function of the applied pressure, we find that the density of states D(ω) exhibits a low-frequency cutoff ω∗, which scales linearly with the number of extra contacts per particle δz. Moreover, for ω<ω∗, our results are consistent with D(ω)∼ω2/ω∗2, a quadratic behavior whose prefactor is larger than what is expected from Debye theory. This surprising result agrees with recent theoretical findings [E. DeGiuli, A. Laversanne-Finot, G. A. Düring, E. Lerner, and M. Wyart, Soft Matter 10, 5628 (2014); S. Franz, G. Parisi, P. Urbani, and F. Zamponi, Proc. Natl. Acad. Sci. U.S.A. 112, 14539 (2015)]. Finally, the degree of localization of the softest low frequency modes increases with compression, as shown by the participation ratio as well as their spatial configurations. Overall, our observations show that emulsions are marginally stable and display non-plane-wave modes up to vanishing frequencies.

    Original languageEnglish (US)
    Article number208001
    JournalPhysical Review Letters
    Issue number20
    StatePublished - Nov 8 2016

    ASJC Scopus subject areas

    • General Physics and Astronomy


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