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DY: Fachverband Dynamik und Statistische Physik

DY 37: Glasses and Glass Transition (joint session DY/CPP)

DY 37.1: Hauptvortrag

Mittwoch, 11. März 2026, 11:15–11:45, ZEU/0118

Topological defects in 2D amorphous ensembles — •Peter Keim — Heinrich-Heine-Universität Düsseldorf

Topological defects are key to understand melting of crystals in two dimensions. A dilute gas of bound thus virtual pairs of dislocations cause the softening of a crystal in the vicinity of melting. If thermal energy is high enough to unbind dislocation pairs, translational order is destroyed and the crystal to melts due to the lack of shear resistance. In an amorphous solid, the concept of topology seems useless for the first glance due to the absence of order. Here, we discuss, how the definition of virtual dislocations can be generalized for a two-dimensional glass. Based on positional data of a binary colloidal monolayer we determine the fugazity of generalized virtual dislocations and measure elasticity close to the glass transition: Youngs modulus gets 16π at melting in surprisingly close analogy to Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) - theory for melting of 2D crystals.

Keywords: Soft Matter; Colloidal Monolayer; 2D Glass; Renormalization Group Theory; KTHNY-Theory