The European Physical Journal E

, Volume 25, Issue 3, pp 277–289 | Cite as

Lehmann effect in a compensated cholesteric liquid crystal: Experimental evidence with fixed and gliding boundary conditions

  • A. Dequidt
  • A. Żywociński
  • P. Oswald
Regular Article


In a recent letter (Europhys. Lett. 80, 26001 (2007)), we have shown that a compensated cholesteric liquid crystal (in which the macroscopic helix completely unwinds) may be subjected to a thermomechanical torque (the so-called Lehmann effect), in agreement with previous findings of Éber and Jánossy (Mol. Cryst. Liq. Cryst. Lett. 72, 233 (1982)). These results prove that one must take into account the chirality of the molecules and the absence of inversion symmetry at the macroscopic scale when deriving the constitutive equations of the phase at the compensation temperature. In this paper, we present the details of our experimental work and a new experiment performed in a sample treated for planar gliding anchoring. The latter experiment, coupled with a numerical simulation, supports the existence of a thermomechanical coupling in a compensated cholesteric.


61.30.-v Liquid crystals 05.70.Ln Nonequilibrium and irreversible thermodynamics 65.40.De Thermal expansion; thermomechanical effects 


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Copyright information

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2008

Authors and Affiliations

  1. 1.Laboratoire de Physique, École Normale Supérieure de Lyon, CNRSUniversité de LyonLyonFrance
  2. 2.Department III, Institute of Physical ChemistryPolish Academy of SciencesWarsawPoland

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