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Phys. Rev. Lett. 100, 180601 (2008) [4 pages]

Experimental Evidence of Non-Gaussian Fluctuations near a Critical Point

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S. Joubaud, A. Petrosyan, S. Ciliberto, and N. B. Garnier
Université de Lyon, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS, 46, Allée d’Italie, 69364 Lyon Cedex 07, France

Received 13 February 2008; published 5 May 2008

The orientation fluctuations of the director of a liquid crystal are measured, by a sensitive polarization interferometer, close to the Fréedericksz transition, which is a second-order transition driven by an electric field. We show that, near the critical value of the field, the spatially averaged order parameter has a generalized Gumbel distribution instead of a Gaussian one. The latter is recovered away from the critical point. The relevance of slow modes is pointed out. The parameter of the generalized Gumbel distribution is related to the effective number of degrees of freedom.

© 2008 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.100.180601
DOI:
10.1103/PhysRevLett.100.180601
PACS:
05.40.−a, 02.50.−r, 05.70.Jk, 64.60.−i