Article,
Measurement of growing dynamical length scales and prediction of the jamming transition in a granular material
Nature Phsyics, (2007)
Abstract
Supercooled liquids and dense colloidal suspensions exhibit
anomalous behaviour known as ‘spatially heterogeneous
dynamics’ (SHD), which becomes increasingly pronounced as
the system approaches the glass transition1–3 . Recently, the
observation of SHD in confined granular packings under slow
shear near the onset of jamming has bolstered speculation that
the two transitions are related4–6 . Here, we report measurements
of SHD in a system of air-driven granular beads, as a function of
both density and effective temperature. On approach to jamming,
the dynamics becomes progressively slower and more spatially
heterogeneous. The rapid growth of timescales and dynamical
length scales characterizing the heterogeneities can be described
both by mode-coupling theory7 and the Vogel–Tammann–
Fulcher (VTF) equation8 , such as in glass-forming liquids. The
value of the control variable at the VTF transition coincides with
point J (refs 9,10), the random close-packed jamming density at
which all motion ceases, in analogy to a zero-temperature ideal
glass transition. Our findings demonstrate further universality
of the jamming concept and provide a significant step forward in
the quest for a unified theory of jamming in disparate systems.
