TY - JOUR
T1 - Novel results of extremely thin substrate-free liquid-crystal films obtained from calorimetric and computer simulation studies
AU - Stoebe, T.
AU - Jiang, I. M.
AU - Huang, S. N.
AU - Jin, A. J.
AU - Huang, Cheng-Cher
PY - 1994/4/1
Y1 - 1994/4/1
N2 - Experimental results from extremely thin free-standing liquid-crystal films have been found to exhibit divergent heat-capacity anomalies in the vicinity of the smectic-A-hexatic-B (SmA-HexB) transition. In fact, the data can be successfully fit to a power-law expression yielding the critical exponent α=0.30±0.04. The results clearly indicate that the transition cannot be described solely in terms of hexatic order and that some additional molecular order must be created in the SmA-HexB transition in these liquid crystals. This transition is therefore not the simple liquid-hexatic transition as had been suggested previously. In light of x-ray diffraction studies indicating the existence of herringbone order in some liquid-crystal samples, Bruinsma and Aeppli formulated a coupled XY hamiltonian as a possible explanation for the anomalous experimental data obtained on the SmA-HexB transition in three dimensions (i.e. bulk samples). Based on our novel calorimetric and optical reflectivity results from thin liquid-crystal films, we have conducted extensive Monte Carlo simulations to explore this model in two-dimensional lattices. These studies have resulted in a number of novel discoveries that reveal important aspects of both the SmA-HexB transition in thin liquid-crystal films and two-dimensional melting phenomena in general.
AB - Experimental results from extremely thin free-standing liquid-crystal films have been found to exhibit divergent heat-capacity anomalies in the vicinity of the smectic-A-hexatic-B (SmA-HexB) transition. In fact, the data can be successfully fit to a power-law expression yielding the critical exponent α=0.30±0.04. The results clearly indicate that the transition cannot be described solely in terms of hexatic order and that some additional molecular order must be created in the SmA-HexB transition in these liquid crystals. This transition is therefore not the simple liquid-hexatic transition as had been suggested previously. In light of x-ray diffraction studies indicating the existence of herringbone order in some liquid-crystal samples, Bruinsma and Aeppli formulated a coupled XY hamiltonian as a possible explanation for the anomalous experimental data obtained on the SmA-HexB transition in three dimensions (i.e. bulk samples). Based on our novel calorimetric and optical reflectivity results from thin liquid-crystal films, we have conducted extensive Monte Carlo simulations to explore this model in two-dimensional lattices. These studies have resulted in a number of novel discoveries that reveal important aspects of both the SmA-HexB transition in thin liquid-crystal films and two-dimensional melting phenomena in general.
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U2 - 10.1016/0378-4371(94)90494-4
DO - 10.1016/0378-4371(94)90494-4
M3 - Article
AN - SCOPUS:0002301856
SN - 0378-4371
VL - 205
SP - 108
EP - 121
JO - Physica A: Statistical Mechanics and its Applications
JF - Physica A: Statistical Mechanics and its Applications
IS - 1-3
ER -