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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)