Regensburg 2004 – scientific programme
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DF: Dielektrische Festkörper
DF 4: Gl
äser II (gemeinsam FV DF/DY)
DF 4.12: Talk
Tuesday, March 9, 2004, 17:30–17:45, H23
A binary colloidal mixture in 2D: An ideal model system for the glass transition — •Hans König — Fachbereich Physik, Universität Konstanz, 78457 Konstanz
Investigating a binary 2D colloidal glass former with a repulsive (1/r3) potential we have measured particle positions as a function of time by video-microscopy. The local packing of the big and small particles as well as the heterogeneous dynamics were analysed depending on the system temperature. Finally, we could describe the amorphous 2D short-range order by local density-optimized triangles. However, there is one triangle for each 3-particle combination of big and small colloids. Regions with structural frustration occur between clusters of optimally packed triangles. For decreasing system temperature the number of densely packed triangles increased and they began to form clusters. For low system temperatures such local density-optimized regions moved cooperatively resulting in heterogeneous dynamics. By structural and dynamical investigations we identify the 2D glass transition as a percolation of local density-optimized triangles, which form a stable frame through the whole glass former. At last, we call this glass description the concept of local density-optimized crystallite clusters.