Berlin 2005 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

DF: Dielektrische Festkörper

DF 7: Gl
äser I (gemeinsam mit FV DY)

DF 7.4: Talk

Monday, March 7, 2005, 11:00–11:15, TU A060

Beta-peak dynamics in the hard-sphere colloidal system — •Matthias Sperl — Duke University, Department of Physics, Box 90305, Durham, NC 27708, USA

The nearly-logarithmic decay of the correlation functions found recently in glass-forming molecular liquids is identified in the data for the mean-squared displacement of the colloidal hard-sphere system at the liquid-glass transition. The solutions of mode-coupling theory (MCT) fit the data well. An asymptotic expansion of the MCT equations of motion explains the nearly-logarithmic decay as a manifestation of the critical relaxation near a simple glass-transition singularity. The later phenomenon is therefore clearly different from the logarithmic decays at higher-order glass-transition singularities. A Cole-Cole formula can be derived rigorously for the nearly-logarithmic relaxation from the leading-order asymptotic expansion. The next-to-leading approximation describes the experimental data for three decades in time.

While previously only known for schematic models, the results identify a beta-peak phenomenon in a microscopic MCT calculation and clarify the origin of this feature of glassy dynamics.