Glassy dynamics in asymmetric binary mixtures of hard spheres

We perform a systematic and detailed study of the glass transition in highly asymmetric binary mixtures of colloidal hard- spheres, combining differential dynamic microscopy experiments, molecular dynamics simulations and theoretical calculations, exploring the whole state diagram and determining the and collective dynamics of both species. Two distinct glassy states involving different dynamical arrest transitions are consistently described, namely, a double glass with the simultaneous arrest of the and collective dynamics of both species, and a single glass of large particles in which the dynamics of the small species remains ergodic. In the single glass scenario, spatial modulations in the collective dynamics of both species occur due to the structure of the large spheres, a feature not observed in the double glass domain. The theoretical results, obtained within the self-consistent generalized Langevin equation formalism, are in agreement with both simulations and experimental data, thus providing the first stringent validation of this theoretical framework in the description of dynamical arrest in highly asymmetric mixtures. Our findings are summarized in a state diagram that classifies the various amorphous states of highly asymmetric mixtures by their dynamical arrest mechanisms.