title: Birefringence in the vicinity of the smectic-A to smectic-C phase transition: Crossover from XY critical to tricritical behavior.
abstract: High-resolution birefringence (Δn) measurements are carried out to probe the critical behavior at the smectic-A-smectic-C (Sm-A-Sm-C) phase transition in a binary system. The critical behavior of this transition is explored with the aid of a differential quotient extracted from the Δn values. The results obtained reveal that the Sm-A-Sm-C and nematic-smectic-A (N-Sm-A) transitions exhibit nonuniversal behaviors with effective exponents lying between the tricritical and three-dimensional XY values and follow two distinctly different curves with decreasing width of the Sm-A and N phases, respectively. The origin of such critical behavior is a unique feature for the respective phase transitions.
authors.affiliation: Department of Physics, University of North Bengal, Siliguri, Darjeeling 734 013, India.
authors.forename: Malay Kumar
authors.initials: MK
authors.lastname: Das
authors.affiliation: Department of Physics, University of North Bengal, Siliguri, Darjeeling 734 013, India.
authors.forename: Susanta
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego Street 2, 00-908 Warsaw, Poland.
authors.forename: Roman
authors.initials: R
authors.lastname: Dabrowski
authors.affiliation: Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego Street 2, 00-908 Warsaw, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Czerwiński