title: Growing dynamical facilitation on approaching the random pinning colloidal glass transition.
abstract: 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.
authors.affiliation: 1] Department of Physics, Indian Institute of Science, Bangalore 560012, India [2].
authors.forename: Shreyas
authors.initials: S
authors.lastname: Gokhale
authors.affiliation: 1] Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India [2].
authors.forename: K
authors.initials: K
authors.lastname: Hima Nagamanasa
authors.affiliation: International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Ganapathy
authors.affiliation: 1] Department of Physics, Indian Institute of Science, Bangalore 560012, India [2] International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Sood