Physics Colloquium
Friday, November 12th, 2004, 4:00 P.M.

Phil Duxbury

Department of Physics and Astronomy
Michigan State University

Emergent geometric structures in complex materials

In this talk I will describe two different mechanisms for the emergence of critical geometric structures in complex materials. The first mechanism operates through the combination of disorder and non-linear response, which can produce spectacular structures, with the most well known being dielectric trees and fracture surfaces. In these cases and many other nonlinear processes, the emergent manifold is of lower dimension than the embedding space. The second mechanism I will discuss is the onset of a percolating cluster of frozen variables at low temperature glassy phase transitions. Though the most well studied spin glass transition is of second order and hence has an associated percolating fractal of frozen variables, many other low temperature glassy models have first order phase transitions. Models of voltage localization in high Tcsuperconductors, current localization in varistors and the onset of rigidity in glasses and proteins will be used to illustrate the general concepts.

http://www.pa.msu.edu/people/duxbury/