Growing dynamical facilitation on approaching the random pinning colloidal glass transition

• Published in: Nature communications Vol. 5; no. 1; p. 4685
• Main Authors: Gokhale, Shreyas, Hima Nagamanasa, K., Ganapathy, Rajesh, Sood, A. K.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.08.2014; Nature Publishing Group
• Subjects: Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms5685

Despite decades of research, it remains to be established whether the transformation of a liquid into a glass is fundamentally thermodynamic or dynamic in origin. Although observations of growing length scales are consistent with thermodynamic perspectives, the purely dynamic approach of the Dynamical Facilitation (DF) theory lacks experimental support. Further, for vitrification induced by randomly freezing a subset of particles in the liquid phase, simulations support the existence of an underlying thermodynamic phase transition, whereas the DF theory remains unexplored. Here, using video microscopy and holographic optical tweezers, we show that DF in a colloidal glass-forming liquid grows with density as well as the fraction of pinned particles. In addition, we observe that heterogeneous dynamics in the form of string-like cooperative motion emerges naturally within the framework of facilitation. Our findings suggest that a deeper understanding of the glass transition necessitates an amalgamation of existing theoretical approaches. It remains a matter of debate whether the glass transition is thermodynamic or dynamic in nature. Here Gokhale et al. examine slow dynamics in a binary colloidal liquid and provide support for the dynamical facilitation approach–a purely dynamic theory of the glass transition.