Regensburg 2019 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 43: Anomalous diffusion / Brownian motion

DY 43.10: Vortrag

Donnerstag, 4. April 2019, 12:30–12:45, H3

Orientational and directional locking of colloidal clusters driving across periodic surfaces — •Xin Cao¹, Emanuele Panizon², Andrea Vanossi^2,3, Nicola Manini⁴, and Clemens Bechinger¹ — ¹Fachbereich Physik, University Konstanz, 78464 Konstanz, Germany — ²International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy — ³CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste, Italy — ⁴Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy

When isolated particles are driven over atomically corrugated crystalline surfaces, their trajectories do not necessarily follow the applied force but become locked to directions imposed by the substrate symmetry. Such directional locking is relevant for the manipulation and steering of nano-objects on surfaces. Contrary to previous studies which have been performed for single particles, here we study the motion of extended crystalline clusters composed of colloidal particles on a periodic surface. We observe that both their orientational and their center-of-mass motion become locked in the presence of a driving force. Contrary to single particles, the locking directions do not coincide with the substrate symmetry, but are determined by the geometrical moiré superstructure of the cluster-substrate contact. For certain incommensurabilities, competing locking directions exist and a cluster may spontaneously switch from one direction to another depending on its size. Our research provides insights to the transport of crystalline islands on top of crystalline surfaces.