Dresden 2014 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 18: Granular Matter / Contact Dynamics
DY 18.8: Vortrag
Mittwoch, 2. April 2014, 11:30–11:45, ZEU 118
Nearly-2D granular packings: A mechanical analogue to frustration in spin systems — •Kirsten Harth1, Alexander Mauney2, Frank Rietz1, and Ralf Stannarius1 — 1Institut für Experimentelle Physik, Otto von Guericke Universität Magdeburg, Germany — 2North Carolina State University, Raleigh, USA
Frustration of antiferromagnetic spins on a triangular lattice represents a fundamental problem in theoretical studies of magnetism, and is usually not experimentally observable on the microscale. Recently, an analogous problem has been investigated on an easily accessible length scale, using colloidal particles in a horizontal cell [1].
In granular materials, similar structures are easily prepared with glass spheres in a quasi-2D vertical cell, the cell thickness being slightly larger than the particle diameter. In nearly-hexagonal packings, some of the spheres attach to the front plate while others attach to the rear plate. By mapping the positions of the glass spheres experimentally, statistics of the degree of frustration are performed. Additionally, the influence of a magnetic field on the frustration statistics is mimicked by tilting the cell with respect to the normal in the gravitation field at well-defined angles, such that rear particles are energetically favoured.
[1] Y. Han, Y. Shokef, A. M. Alsayed, P. Yunker, T. C. Lubensky, Nature 7595, p. 898 (2008)