Structures of Local Rearrangements in Soft Colloidal Glasses
We image local structural rearrangements in soft colloidal glasses under small periodic perturbations inducedbythermal cycling.Local structuralentropy S2 positivelycorrelateswith observedrearrangements in colloidal glasses. The high S2 values of the rearranging clusters in glasses indicate that fragile regions in glassesarestructurally less correlated,similar tostructuraldefectsincrystallinesolids.Slow-evolvinghigh S2 spotsarecapableofpredictinglocalrearrangementslongbeforetherelaxationsoccur,whilefluctuationcreated high S2 spots best correlate with local deformations right before the rearrangement events. Local freevolumesarealsofoundtocorrelatewithparticlerearrangements atextremevalues,althoughtheability to identify relaxation sites is substantially lower than S2. Our experiments provide an efficient structural identifier for the fragile regions in glasses and highlight the important role of structural correlations in the physics of glasses.