Observation of relaxation modes in room temperature ferroelectric liquid crystal mixtures |
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Authors: | K K Raina Arvind K Gathania Buta Singh |
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Institution: | (1) School of Basic and Applied Sciences, Thapar Institute of Engineering and Technology, 147 004 Patiala, India;(2) Department of Physics, Punjabi University, 147 002 Patiala, India |
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Abstract: | The dielectric measurements in SmC* and SmA phases of a room temperature ferroelectric liquid crystal mixture FLC-6980 in
the cells of different thickness in planer alignment have been carried out in the frequency range 100 Hz to 1 MHz. A relaxation
mode (called NRM) whose dielectric increment is less than the Goldstone mode has been observed in the SmC* phase. This mode
appears due to the surface effect. Goldstone mode and the soft mode was observable in the vicinity of SmC*-SmA transition
temperature (T
C*A). The dielectric parameters of the Goldstone mode, new mode and the soft mode have been studied as a function of frequency
and temperature. The calculated values for fNRM, δεNRM and distribution parameter αNRM are found to be 325 kHz, 6 and 0.156 for 5μm thick planer cell at 37°C. It is seen that in the vicinity of theT
C*A, soft mode obeys the Curie-Weiss law given by mean field theory. The results have been compared with materials of large spontaneous
polarization. |
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Keywords: | Ferroelectric liquid crystal dielectric increment relaxation mode Goldstone mode soft mode |
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