Generalized Landau model of ferroelectric liquid crystals

Carlsson, Tomas; Žekš, B.; Levstik, A.; Filipič, C.; Levstik, I.; Blinc, R.

doi:10.1103/physreva.36.1484

Cited by 135 publications

(86 citation statements)

References 11 publications

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“…This looks like previous theories [9,10,15] which make use only of the 2D-uniaxial invariant missing somewhat the other terms which are at the origin of the Hamaneh- Taylor (H&T) theory [23,26,27].…”

Section: B Landau -De Gennes Free Energysupporting

confidence: 72%

Continuum theory of tilted chiral smectic phases

Marcerou

2010

Phys. Rev. E

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We demonstrate that the sequence of distorted commensurate phases observed in tilted chiral smectics is explained by the gain in electrostatic energy due to the lock-in of the unit cell to a number of layers which is the integer closest to the ratio pitch over thickness of the subjacent Sm-C * α phase. We also explain the sign change of the helicity in the middle of the sequence by a balance between two twist sources one intrinsic and another due to the distortion of the Sm-C * α .

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Section: B Landau -De Gennes Free Energysupporting

confidence: 72%

Continuum theory of tilted chiral smectic phases

Marcerou

2010

Phys. Rev. E

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“…[13,16,17] The behaviour of the SmC * phases in external magnetic and electric fields has also been intensively studied. [13] One of the first detailed investigations about unwinding of the helical axis by a magnetic field parallel to it was reported by Musevic et al in 1982.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Magnetic Field on the Supramolecular Structure of Chiral Smectic C Phases: ²H NMR Studies

et al. 2007

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We present a theoretical and experimental (2)H NMR study of the effect of external magnetic fields on the supramolecular organization of chiral smectic liquid-crystalline mesophases, such as SmC* and re-entrant SmC*. Three experimental cases in which the supramolecular helical structure of the smectic C* phase is unwound by a magnetic field (H), parallel to the helical axes of this phase, are discussed in detail. Unwinding of the helical structure is described by using a theoretical model based on the Landau-de Gennes theory, which allows us to explain the transition temperatures among the SmA, SmC*, and uSmC* phases. The energy-density behavior in the vicinity of the transitions and the value of the critical magnetic field H(C) for unwinding the helical structure are discussed by applying this model to three ferroelectric smectogens (MBHB, 11EB1M7, ZLL7/*), which are studied by (2)H NMR spectroscopy at different magnetic fields (from 2.4 to 9.4 Tesla). Furthermore, the tilt angle of the three smectogens in the SmC* phase has been directly evaluated, for the first time, by comparing the quadrupolar splittings at different magnetic fields. In one case, (2)H NMR angular measurements are used to obtain the tilt angle in the re-entrant smectic C phase.

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“…Ferroelectric liquid crystals have been the subject of various experimental and theoretical studies [1][2][3][4][5][6][7][8][9][10][11][12]. As a function of temperature under fixed pressures or concentrations, the physical quantities such as the spontaneous polarization, tilt angle, dielectric constant, specific heat, and so forth.…”

Section: Introductionmentioning

confidence: 99%

“…in the mean field models. A bilinear coupling between the spontaneous polarization and the tilt angle (Pθ coupling) [5,7] and the biquadratic coupling (P 2 θ 2 coupling) [3,4] have been considered in the mean field models mainly for the smectic AC (or AC * ) transitions. We have also studied the AC or AC * transitions using the biquadratic [14][15][16][17][18] and both the bilinear and biquadratic couplings [19,20] in our earlier studies.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Dielectric Constant as a Function of Temperature at Constant Electric Fields for the Smectic A-Smectic G Transition in A6

Yurtseven

Kilit

2012

ISRN Condensed Matter Physics

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The temperature dependence of the dielectric constant is studied under some fixed electric fields for the smectic G-(tilted-) smectic A (orthogonal) transition of the ferroelectric liquid crystal of compound A6. For this study, a mean field model with the quadrupole-quadrupole interactions is introduced. By fitting the inverse dielectric susceptibility from the mean field model to the experimental data from the literature, the observed behaviour of the dielectric constant is described satisfactorily for the smectic AG transition in A6. The transition temperature induced by an external electric field is also discussed for this ferroelectric compound.

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Generalized Landau model of ferroelectric liquid crystals

Cited by 135 publications

References 11 publications

Continuum theory of tilted chiral smectic phases

Continuum theory of tilted chiral smectic phases

Effect of the Magnetic Field on the Supramolecular Structure of Chiral Smectic C Phases: ²H NMR Studies

Analysis of the Dielectric Constant as a Function of Temperature at Constant Electric Fields for the Smectic A-Smectic G Transition in A6

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Generalized Landau model of ferroelectric liquid crystals

Cited by 135 publications

References 11 publications

Continuum theory of tilted chiral smectic phases

Continuum theory of tilted chiral smectic phases

Effect of the Magnetic Field on the Supramolecular Structure of Chiral Smectic C Phases: 2H NMR Studies

Analysis of the Dielectric Constant as a Function of Temperature at Constant Electric Fields for the Smectic A-Smectic G Transition in A6

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Effect of the Magnetic Field on the Supramolecular Structure of Chiral Smectic C Phases: ²H NMR Studies