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Science 3 February 1995:
Vol. 267. no. 5198, pp. 651 - 654
DOI: 10.1126/science.267.5198.651
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Articles

Stress-induced Vortex Line Helixing Avalanches in the Plastic Flow of a Smectic A Liquid Crystal

Richard A. Herke 1, Noel A. Clark 1, and Mark A. Handschy 1

1 Condensed Matter Laboratory, Department of Physics, University of Colorado, Boulder, CO 80309, USA.

Dynamic surface force measurements of the response of a smectic A to layer normal stress exhibited time dependence for topological events in which single smectic layers were added or removed. Single layer-sized jumps in sample thickness had a rapid component of duration of sim1 second that produced most of the change in separation, but that was heralded by a slow precursor acceleration in separation, which began up to a few hundred seconds before. This avalanche-like dynamic signature is consistent with a relaxation mechanism based on the Glaberson-Clem-Bourdon instability of vortex lines (screw dislocations) in the smectic order parameter.

Submitted on July 13, 1994
Accepted on November 21, 1994

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Science. ISSN 0036-8075 (print), 1095-9203 (online)