title: Superlattice structures observed in the extraordinary phase sequence and analyzed by the phenomenological Landau model and the partially molecular model.
abstract: We draw several electric-field-temperature (E-T) phase diagrams with electric-field-induced birefringence contours in the nOHFBBB1M7 (n=10) and nOTBBB1M7 (n=11) (C11) mixture system by changing the C11 concentration carefully; some of the mixtures show the unusual extraordinary phase sequence where subphases with the four-, five-, and six-layer superlattice structures emerge above the smectic-C(*) main phase. We try to understand the results in terms of two complementary models that have so far been proposed: the phenomenological Landau model of phase transitions by Dolganov et al. [P. V. Dolganov et al., Phys. Rev. E 86, 020701(R) (2012)] and the partially molecular Emelyanenko-Osipov model [A. V. Emelyanenko and M. A. Osipov, Phys. Rev. E 68, 051703 (2003)]. The observed E-T phase diagram can be well reproduced by the phenomenological model. An emergence of the subphase with the four-layer superlattice structure above smectic-C(*) is also understandable in terms of the partially molecular model. We discuss the pros and cons of the two models as well.
authors.affiliation: Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland.
authors.forename: K L
authors.initials: KL
authors.lastname: Sandhya
authors.forename: A D L
authors.initials: AD
authors.lastname: Chandani
authors.forename: Atsuo
authors.initials: A
authors.lastname: Fukuda
authors.forename: S
authors.initials: S
authors.lastname: Kumar
authors.forename: Jagdish K
authors.initials: JK
authors.lastname: Vij