Detailed heat-capacity measurements have been carried out on free-standing liquid-crystal films of n-heptyl-4’-n-pentyloxybisphenyl-4-carboxylate to investigate the nature of transitions related to surface crystal-E order. Distinct thermal hystereses are observed. Upon heating from the temperature range exhibiting surface crystal-E order and interior hexatic order, anomalous effects on the interior hexatic-B–smectic-A transition, which strongly depend on the film thickness, are evident.

• Received 25 August 1992

DOI:https://doi.org/10.1103/PhysRevA.46.R6162