Local particle rearrangements in a two-dimensional binary colloidal glass former

Abstract

In a two‐dimensional (2D) glass former composed of two kinds of different sized and repulsively interacting colloidal particles, the time‐dependent particle positions were observed by video‐microscopy. Analyzing the local particle arrangements by 3‐point correlation functions, we find four different local density‐optimized configurations of nearest neighboring particles, which we call elementary triangles (ET), one for each three‐particle combination of small and big particles. These four ET form a random tiling in the 2D monolayer, which is not space filling. Therefore, a heterogeneous local particle packing does not have long‐range order and shows structural frustrations. Furthermore, an analysis of structural relaxations, using triangles of nearest neighboring particles (TNNP) in the monolayer, suggests that hopping processes are the reason for the rearrangements of the particles. In the outlook, we propose a concept of local density‐optimized crystallite‐clusters to describe the glass transition as a percolation of stable local density‐optimized triangles.