Pavel Dolganov

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New mechanisms of droplet nucleation and self-organization in ferroelectric membranes are described. The droplets may be accompanied by different number of topological defects (zero, one, two) whose location may be on the droplet boundary or in the membrane. Nucleation and self-organization of droplets with total topological charge S = 0 , S = + 1 and S = -(More)
We observed, in free-standing films of antiferroelectric liquid crystal, dependence of the wall structure on orientation of walls with respect to the external field direction and on parity of number of smectic layer in the film. These observations are explained by anisotropy of two-dimensional elastic constants and by dependence of polarization direction on(More)
Optical reflectivity studies have been conducted upon thin free-standing films of an antiferroelectric liquid crystal possessing the bulk phase sequence Sm C(*)(A)-Sm C(*)(alpha)-Sm A. Electrically induced field independent and field dependent structural transformations were observed above the bulk Sm C(*)(A)-Sm C(*)(alpha) transition temperature. The(More)
We study the topology of the c-director field near topological defects with point core and with a droplet in the core of the defect in nonpolar smectic-C and ferroelectric smectic-C* freestanding films using polarized optical microscopy. Free and confined geometry of topological defects and droplets with strong outer boundary condition are compared. The(More)
Droplets in smectic free-standing films interact due to elastic distortion of the c-director field and formation of topological defects. Our experiments show that chirality of the liquid-crystal medium plays a key role in the interaction between droplets. We find that the configuration of the c-director field near the droplets and the position of the(More)
Density of photonic states ρ(ω), group v(g), and phase v(ph) velocity of light, and the dispersion relation between wave vector k, and frequency ω(k) were determined in a cholesteric photonic crystal. A highly sensitive method (measurement of rotation of the plane of polarization of light) was used to determine ρ(ω) in samples of different quality. In(More)
Photosensitive smectic membranes of pure liquid crystal (LC) were studied under white light illumination. A thickness increase is observed in the illuminated film area. Appropriate light and thermal conditions lead to a thickening layer by layer process. This unusual phenomenon is opposite to the well-known step-by-step thinning transitions under heating.(More)
Recently Wang [Phys. Rev. Lett. 104, 027801 (2010)] discovered a novel smectic-C* liquid-crystal commensurate structure with six-layer period. Challenged by this discovery, we show that the observed novel structure and the unusual sequence of polar phases can be explained in the framework of the discrete Landau model of phase transitions with a(More)
A discrete phenomenological model of antiferroelectric liquid crystals is used to study the structures and phase transitions in bulk samples and thin films. An important ingredient of our investigations is minimization of the free energy with respect to the phase and modulus of the order parameter. A simple version of the free energy, which contains only(More)
The transformation of a chiral antiferroelectric liquid crystal in an electric field was calculated. Minimization of the free energy was performed with respect to both the phase and the modulus of the two-component order parameter. Competition between the electric field, which favors a planar structure, and chirality and the anticlinic ordering leads to(More)