Investigating the nematic--smectic-[ital A] transition by capillary-length measurements near an apparent tricritical point

Journal Article · Tue Feb 28 23:00:00 EST 1995 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States)

DOI:https://doi.org/10.1103/PhysRevE.51.2223· OSTI ID:6544523

Tamblyn, N ^[1]; Oswald, P ^[2]; Miele, A ^[1]; Bechhoefer, J ^[1]

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1. Department of Physics, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 (Canada)
2. Laboratoire de Physique, Ecole Normale Superieure de Lyon, 46, allee d'Italie, 69364 Lyon Cedex 07 (France)

What is the order of the nematic--smectic-[ital A] ([ital NA]) transition The answer to this question has flip-flopped over the years as ever more sophisticated theories and ever more careful experiments have addressed the issue. The Landau theory predicts that the transition can be either first or second order, depending on material parameters. de Gennes and McMillan [Solid State Commun. 10, 753 (1972); Phys. Rev. A 14, 1238 (1971)] showed that nematic fluctuations would drive the transition to first order as the temperature of the [ital NA] transition approached that of the nematic-isotropic transition. Halperin, Lubensky, and Ma [Phys. Rev. Lett. 32, 292 (1974)] (HLM) then argued that the effect of nematic fluctuations is more subtle and concluded that the transition is always at least weakly first order. Monte Carlo simulations indicate, however, that for a large enough nematic range, the transition becomes second order. We investigate the order of the [ital NA] transition experimentally by measuring the capillary length (ratio of the surface tension to the latent heat) near an apparent tricritical point in a binary liquid-crystal mixture. Our measurements confirm the existence of the extra free-energy term predicted by the HLM theory and yield, as a by-product, surface-tension measurements of the [ital NA] interface. Although we cannot currently detect the tricritical point suggested by numerical work, we have not approached any fundamental sensitivity limits either.

• OSTI ID: 6544523
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States), Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States) Vol. 51:3; ISSN PLEEE8; ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

665000* -- Physics of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BINARY MIXTURES
CRYSTAL-PHASE TRANSFORMATIONS
CRYSTALS
DISPERSIONS
ENERGY
FLUIDS
FREE ENERGY
LIQUID CRYSTALS
LIQUIDS
MIXTURES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SURFACE PROPERTIES
SURFACE TENSION
THERMODYNAMIC PROPERTIES