Order-Agnostic Structural Correlations in Colloidal Vitrification and Devitrification

Traditional structural probes reveal little change associated with the rapid slowing down of dynamics as liquids turn into glasses. This review synthesizes results from colloid experiments, primarily real-space studies conducted over roughly the past decade, aimed at resolving the disconnect between structure and dynamics. We examine how order-agnostic measures—excess entropy, point-to-set length scales, machine-learned softness, intermediate-range order, and soft modes—provide a robust link between static structure and dynamics. A key theme that emerges from these studies is the need to consider structural correlations that extend well beyond the first nearest-neighbor shell. Finally, we discuss the devitrification of a colloidal glass and draw upon findings that demonstrate how the hidden structure in the glassy state dictates the subsequent crystallization pathway. Taken together, these studies help establish a quantitative, structure-based framework of glass formation and stability.