Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 62: Fluids and Interfaces III

CPP 62.9: Vortrag

Donnerstag, 23. März 2017, 17:15–17:30, ZEU 255

Aubry Transition in 2D Colloidal Crystals — •Thorsten Brazda — 2. Physikalisches Institut, Universität Stuttgart Pfaffenwaldring 57, 70550 Stuttgart, Germany

According to Aubry et al., the static friction of a monolayer of interacting particles sliding across a crystalline surface can completely vanish in incommensurate systems leading to superlubricity [1]. For a given amplitude of the substrate potential, there exists a critical value of the particle interaction strength above which the monolayer elastically slides across the substrate even for an infinitesimally small driving force. Below that value, the chain becomes locked to the substrate which leads to a finite static friction force. In our experiments we investigate an extended 2D colloidal crystal which is driven across a (111) substrate, the latter created by a laser interference pattern. When the lattice constant of the colloidal crystal is incommensurate with the length scale of the underlying substrate potential, we observe the disappearance of static friction for non-zero substrate strengths. In agreement with recent numerical simulations [2], our results suggest, that this Aubry transition is of first order and that this dynamical phase transition is accompanied by characteristic structural changes in the monolayer.

1. M. Peyrard, J. Phys. Chem. C: Solid State Physics, 1983. 16(9): p. 1593.

2. D. Mandelli, Physical Review B, 2015. 92(13): p. 134306.