Browsing by Author "SONG, JANG-KUN"
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Anomalous dependence of response time on the electric field in an electroclinic liquid crystal with large induced tilt and polarization
VIJ, JAGDISH; MANNA, UTTAM; SONG, JANG-KUN (2009)We investigate the response time of an electroclinic liquid crystal with large induced tilt and polarization (de Vries smectic A*). The response time is found to increase with the increase in electric field up to a threshold ... -
Antiferroelectric dielectric relaxation processes and the interlayer interaction in antiferroelectric liquid crystals
VIJ, JAGDISH; SONG, JANG-KUN; FUKUDA, ATSUO; MANNA, UTTAM (2008)Antiphase relaxation process of antiferroelectric phase is investigated in binary mixtures of antiferroelectric and ferroelectric liquid crystalline compounds. It is found that the frequency of the antiphase mode ranges ... -
Conoscopy of chiral smectic liquid crystal cells
VIJ, JAGDISH; SONG, JANG-KUN (2008)The conoscopic method for investigating the optical properties of a liquid crystal cell is studied with the aim of determining the effects of the approximations used in the calculation on the results. We confirm that the ... -
Dynamic mechanism of the ferroelectric to antiferroelectric phase transition in chiral smectic liquid crystals
VIJ, JAGDISH; FUKUDA, ATSUO; SONG, JANG-KUN (2008)We report on the observation of V-shaped switching in a ferroelectric liquid crystal cell over a wide range of temperatures. Results of the optical transmittance in the visible region give us the helical pitch for various ... -
Effect of cell surfaces on the stability of chiral smectic- C phases
VIJ, JAGDISH; MANNA, UTTAM; SONG, JANG-KUN (2008)The effect of surfaces on the stability of smectic-C* (SmC*) variant phases is investigated. The results obtained using dielectric spectroscopy by varying the cell thickness show that the temperature ranges of SmC<sub>al ... -
Electric-field-dependent dielectric response in the de Vries-type smectic- A* phase possessing local orientational order with nanoscale correlation length
VIJ, JAGDISH; MANNA, UTTAM; SONG, JANG-KUN (2008)The dielectric strength is shown to increase and the relaxation frequency to decrease for a large temperature range up to a certain value of the electric field in the smectic-A* phase. This behavior contrasts to that ... -
Electro-optic and dielectric study of the de Vries-type smectic- A phase exhibiting transitions to smectic- CA and smectic- C phases
PANARIN, YURI; VIJ, JAGDISH; FUKUDA, ATSUO; MANNA, UTTAM; SONG, JANG-KUN (2008)Mixtures of different compositions of an antiferroelectric liquid crystal compound that exhibits direct smectic-A Sm-A -smectic-CA Sm-CA transition with a ferroelectric liquid crystal compound that exhibits Sm-A -smectic-C ... -
Experimental study of high-temperature smectic- C FI2 phase in chiral smectic liquid crystals that exhibit phase-sequence reversal
VIJ, JAGDISH; SONG, JANG-KUN; PANARIN, YURI (2008)We report the results of an experimental study of a recently observed phase sequence reversal of smectic-C<sub>FI2</sub><sup>*</sup> [SmC*(qT=1/2); a four layer antiferroelectric] phase appearing in the temperature range ... -
Gradual phase transition between the smectic- C* and smectic- CA* phases and the thresholdless antiferroelectricity
VIJ, JAGDISH; SONG, JANG-KUN; FUKUDA, ATSUO (2008)We have constructed the phase diagrams for a binary-mixture system of antiferroelectric and ferroelectric liquid-crystalline materials in both thick and thin cells. In the phase diagrams the boundary between the smectic-C* ... -
Interlayer interactions and the dependence of biaxiality of the chiral smectic- C* phase on electric field in the helical unwinding process
VIJ, JAGDISH; SONG, JANG-KUN (2007)We investigate the unwinding process of pure and racemized mixtures of 1-methylheptyloxycarbonyl phenyl-4 -carboctyloxy-biphenyl-4-carboxylate MHPOOCBC in homeotropic cells by studying i the optical texture under ... -
Mechanism of field-induced unwinding of SmC* helix and biasfield dependencies of dielectric permittivity and effective polarization
VIJ, JAGDISH; SONG, JANG-KUN; MANNA, UTTAM (2008)We propose an unwinding model based on helical fractures confirmed by spectroscopic and microscopic observations. This model combined with the fixed helical pitch can explain the various physical phenomena observed in ... -
Solitary wave propagation in antiferroelectric liquid crystal cells and the quadrupolar term in the interlayer interaction
SONG, JANG-KUN; VIJ, JAGDISH KUMAR (American Physics Society, 2007)Planar antiferroelectric liquid crystal (AFLC) cells exhibit propagating solitary waves. By measuring the retardation and the apparent tilt angle, we find that the conventional model for the solitary wave propagation in ... -
Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells
VIJ, JAGDISH; SONG, JANG-KUN (2008)Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells controlled by surface anchoring of the alignment layers is investigated for different conditions of alignment on the two opposite surfaces. ... -
V-shaped electro-optic response observed in a chiral ferroelectric smectic liquid crystal
VIJ, JAGDISH; PANARIN, YURI; SONG, JANG-KUN (2008)We report on the observation of V-shaped switching in a ferroelectric liquid crystal cell over a wide range of temperatures. Results of the optical transmittance in the visible region give us the helical pitch for various ...