Theoretical model of the frequency and temperature dependence of the complex dielectric constant of ferroelectric liquid crystals near the smectic-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">C</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">*</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>–smectic-<i>A</i>phase transition

Carlsson, Tomas; Žekš, B.; Filipič, C.; Levstik, A.

doi:10.1103/physreva.42.877

Cited by 228 publications

(87 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar behaviour has been reported for Goldstone mode relaxation frequencies before. 62,64,65 It might be caused by the competition between the temperature dependence of the elastic constant and that of the viscosity in the SmC* phase (equation (14)) as given by 66 ~ η (14) where is an effective elastic constant and  the viscosity for a director reorientation along the tilt cone.…”

Section: -63mentioning

confidence: 99%

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

Al-Zangana

Turner

Dierking

2017

Journal of Applied Physics

View full text Add to dashboard Cite

The electro-optic and dielectric properties of barium titanate, BaTiO 3 , nanoparticle (NP) doped nematic and ferroelectric liquid crystal materials were examined with respect to different size and concentration of the NPs. Smaller size paraelectric NPs (≈80nm) are compared to larger, ferroelectric NPs (≈240nm). It is found that for concentrations larger than 0.5vol% the ferroelectric NPs exhibit an increasing effect on the electro-optic response of the nematic liquid crystal, which is demonstrated by the enhancement of the dielectric anisotropy. This could be induced by the coupling of the electrical dipole moments in the spherical NPs with the LC director field. The electro-optical properties of the SmC* phase, like tilt angle Θ, switching time and spontaneous polarisation are found to be independent of the concentration and size of the NPs. The rotational viscosity calculated from response times, polarization reversal current and dielectric properties is comparable for all three methods employed and practically independent of particle concentration and size. The relaxation frequency of the Goldstone mode is higher in the ferroelectric NPs suspensions of 2.0vol% as compared to the smaller paraelectric NPs.

show abstract

Section: -63mentioning

confidence: 99%

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

Al-Zangana

Turner

Dierking

2017

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…where χ E = ∂ P z /∂E is the dielectric susceptibility of the Goldstone mode [24,25]. The above dielectric tensor is characterized by the three generally different principal values (eigenvalues) and the corresponding optical axes (eigenvectors) as follows:…”

Section: B Orientational Kerr Effectmentioning

confidence: 99%

“…where χ E = ∂ P z /∂E is the dielectric susceptibility of the Goldstone mode [24,25] and P z = P s cos . Similarly, the averages that enter the formulas for the elements of the effective dielectric tensor (54) can be expressed in terms of the electric field parameter α E as follows:…”

Section: Appendix C: Averaging Over Flc Helical Structuresmentioning

confidence: 99%

Optics of short-pitch deformed-helix ferroelectric liquid crystals: Symmetries, exceptional points, and polarization-resolved angular patterns

Kiselev

Chigrinov

2014

Phys. Rev. E

View full text Add to dashboard Cite

In order to explore electric-field-induced transformations of polarization singularities in the polarizationresolved angular (conoscopic) patterns emerging after deformed-helix ferroelectric liquid crystal (DHFLC) cells with subwavelength helix pitch, we combine the transfer matrix formalism with the results for the effective dielectric tensor of biaxial FLCs evaluated using an improved technique of averaging over distorted helical structures. Within the framework of the transfer matrix method, we deduce a number of symmetry relations and show that the symmetry axis of L lines (curves of linear polarization) is directed along the major in-plane optical axis which rotates under the action of the electric field. When the angle between this axis and the polarization plane of incident linearly polarized light is above its critical value, the C points (points of circular polarization) appear in the form of symmetrically arranged chains of densely packed star-monstar pairs. We also emphasize the role of phase singularities of a different kind and discuss the enhanced electro-optic response of DHFLCs near the exceptional point where the condition of zero-field isotropy is fulfilled.

show abstract

“…The free-energy density g͑z͒ is given by a Landau expansion in order parameters ͑tilt angle͒, P ͑polarization͒, and ͑Sm A order parameter͒. 3,7 Assuming the coupling between the primary order parameters of the Sm C * and Sm A phases under the application of strong bias, the g͑z͒ can be written as …”

Section: -3mentioning

confidence: 99%

“…Theoretical as well as experimental studies had been carried out by dielectric spectroscopy in both Sm C * and Sm A phases revealing the Goldstone mode in Sm C * phase due to the phason fluctuations and soft mode in Sm A phase due to tilt fluctuations. 2,3 The existence of soft mode in Sm C * phase has been observed by applying strong enough bias voltage to restrict the phason fluctuations or helix unwinding near T c .…”

Section: Introductionmentioning

confidence: 99%

Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals

Choudhary¹,

Kaur²,

Prakash³

et al. 2008

Journal of Applied Physics

View full text Add to dashboard Cite

The behavior of soft mode range with respect to the temperature width of smectic A ͑Sm A͒ phase has been studied in four different ferroelectric liquid crystal ͑FLC͒ materials in the frequency range 10 Hz-10 MHz. The studies have been carried out in a planarly well aligned cells at different temperatures and different bias fields in Sm C * and Sm A phases. Dielectric studies of these FLCs near Sm C * -Sm A phase transition show that the temperature range of soft mode relaxation frequency phenomenon varies with the temperature width of Sm A phase. The dependence of tilt angle on temperature shows the nature of the order of transition at Sm C * -Sm A phase. The coupling between order parameters of Sm C * and Sm A phase influences the soft mode and phase transition in Sm C * and Sm A phases.

show abstract

Theoretical model of the frequency and temperature dependence of the complex dielectric constant of ferroelectric liquid crystals near the smectic-C*–smectic-Aphase transition

Cited by 228 publications

References 24 publications

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

Optics of short-pitch deformed-helix ferroelectric liquid crystals: Symmetries, exceptional points, and polarization-resolved angular patterns

Effect of smectic A temperature width on the soft mode in ferroelectric liquid crystals

Contact Info

Product

Resources

About