DOI: https://doi.org/10.30970/jps.01.535
THE RELAXATION PHENOMENON IN PROPER UNIAXIAL FERROELECTRIC-SEMICONDUCTOR CRYSTALS Sn2P2S(Se)6 WITH INCOMMENSURATE PHASE
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Journal of Physical Studies 1(4), 535–543 (1997)
DOI: https://doi.org/10.30970/jps.01.535 THE RELAXATION PHENOMENON IN PROPER UNIAXIAL FERROELECTRIC-SEMICONDUCTOR CRYSTALS Sn2P2S(Se)6 WITH INCOMMENSURATE PHASE |
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Yu. Vysochanskii, A. Molnar
Institute of Solid State Physics and Chemistry, Uzhgorod University
46 Pidhirna Str., UA294000, Uzhgorod, Ukraine
For ferroelectric–semiconductor crystals Sn$_2$P$_2$S(Se)$_6$ the relaxation of electron subsystem determines the Lifshitz point shift on the phase diagram and the pinning of order parameter wave (memory effect) in the incommensurate phase. For these proper uniaxial ferroelectrics both effects are agreeably described by the phenomenological model, which assumes: the renormalization of the spatial dispersion of the stiffness coefficient for the order parameter fluctuations due to the relaxational variation of the charge carriers concentration on the impurity energy level in the forbidden band of the crystal; the local centres energy modulation, caused by the non-uniform static field of the order parameter in the IC-phase leading to the appearance of concentration-wave of the charge carriers.