title: Smectic-Calpha*-smectic-C* phase transition and critical point in binary mixtures.
abstract: We have investigated the smectic-Calpha*-smectic-C* (SmCalpha*-SmC*) transition in a series of binary mixtures with resonant x-ray diffraction, differential optical reflectivity, and heat capacity measurements. Results show that the phases are separated by a first-order transition that ends at a critical point. We report the observation of such a critical point. We have proposed the appropriate order parameter and obtained values of two critical exponents associated with this transition. The values of the critical exponents suggest that long-range interactions are present in the SmCalpha*-SmC* critical region.
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Liu
authors.forename: S T
authors.initials: ST
authors.lastname: Wang
authors.forename: B K
authors.initials: BK
authors.lastname: McCoy
authors.forename: A
authors.initials: A
authors.lastname: Cady
authors.forename: R
authors.initials: R
authors.lastname: Pindak
authors.forename: W
authors.initials: W
authors.lastname: Caliebe
authors.forename: K
authors.initials: K
authors.lastname: Takekoshi
authors.forename: K
authors.initials: K
authors.lastname: Ema
authors.forename: H T
authors.initials: HT
authors.lastname: Nguyen
authors.forename: C C
authors.initials: CC
authors.lastname: Huang