Measurement of correlations between low-frequency vibrational modes and particle rearrangements in quasi-two-dimensional colloidal glasses

摘要

We investigate correlations between low-frequency vibrational modes andrearrangements in two-dimensional colloidal glasses composed of thermosensitivemicrogel particles which readily permit variation of sample packing fraction.At each packing fraction, the particle displacement covariance matrix ismeasured and used to extract the vibrational spectrum of the "shadow" colloidalglass (i.e., the particle network with the same geometry and interactions asthe sample colloid but absent damping). Rearrangements are induced bysuccessive, small reductions in packing fraction. The experimental resultssuggest that low-frequency quasi-localized phonon modes in colloidal glasses,i.e., modes that present low energy barriers for system rearrangements, arespatially correlated with rearrangements in this thermal system.