Selected Macroscopic Consequences of Tetrahedratic Order

Brand, H. R.; Cladis, P. E.; Pleiner, Harald

doi:10.1080/00150190490509656

Cited by 12 publications

(11 citation statements)

References 29 publications

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“…At the microscopic level it was studied by Fel [38,39], by Romano [40], and in LPW. Phenomenological, macroscopic consequences of a tetrahedratic order were discussed in detail by Cladis, Brand, and Pleiner [41][42][43]. Symmetry classification of orientational structures that combine tensor order parameters of different ranks has been carried out by and Lubensky and Radzihovsky [22] and by Mettout [44].…”

Section: Modelmentioning

confidence: 99%

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Tetrahedratic mesophases, chiral order, and helical domains induced by quadrupolar and octupolar interactions

Trojanowski

Paja̧k²,

Longa

et al. 2012

Phys. Rev. E

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We present an exhaustive account of phases and phase transitions that can be stabilized in the recently introduced generalized Lebwohl-Lasher model with quadrupolar and octupolar microscopic interactions [L. Longa, G. Pająk, and T. Wydro, Phys. Rev. E 79, 040701(R) (2009)]. A complete mean-field analysis of the model, along with Monte Carlo simulations allows us to identify four distinct classes of the phase diagrams with a number of multicritical points where, in addition to the standard uniaxial and biaxial nematic phases, the other nematic like phases are stabilized. These involve, among the others, tetrahedratic (T), nematic tetrahedratic (N(T)), and chiral nematic tetrahedratic (N(T)(*)) phases of global T(d), D(2d), and D(2) symmetry, respectively. Molecular order parameters and correlation functions in these phases are determined. We conclude with generalizations of the model that give a simple molecular interpretation of macroscopic regions with opposite optical activity (ambidextrous chirality), observed, e.g., in bent-core systems. An estimate of the helical pitch in the N(T)(*) phase is also given.

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Section: Modelmentioning

confidence: 99%

“…The proportionality of V c to (p i + p j ) and Eq. (43) also imply that V c is relevant given that p i = p j . For states of opposite parity (p i = −p j ) the V c term vanishes.…”

Section: Twisted Molecular Configurations and Ambidextrous Chiralitymentioning

confidence: 99%

Tetrahedratic mesophases, chiral order, and helical domains induced by quadrupolar and octupolar interactions

Trojanowski

Paja̧k²,

Longa

et al. 2012

Phys. Rev. E

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“…This rather surprising phenomenon can be explained by the simultaneous presence of the usual quadrupolar orientational order as well as of tetrahedratic (octupolar) order [12]. The latter, suggested first for the application to the field of liquid crystals by Fel [13], can also have numerous other fascinating macroscopic consequences [14][15][16].…”

Section: Introductionmentioning

confidence: 97%

Macroscopic dynamics of polar nematic liquid crystals

2006

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We present the macroscopic equations for polar nematic liquid crystals. We consider the case where one has both, the usual nematic director, n[over ] , characterizing quadrupolar order as well as the macroscopic polarization, P , representing polar order, but where their directions coincide and are rigidly coupled. In this case one has to choose P as the independent macroscopic variable. Such equations are expected to be relevant in connection with nematic phases with unusual properties found recently in compounds composed of banana-shaped molecules. Among the effects predicted, which are absent in conventional nematic liquid crystals showing only quadrupolar order, are pyro-electricity and its analogs for density and for concentration in mixtures as well as a flow alignment behavior, which is more complex than in usual low molecular weight nematics. We also discuss the formation of defect structures expected in such systems.

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“…The major part of the investigations on the influence of octupolar order for fluid and gel-like systems has been in the field of liquid crystals [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] starting with the pioneering papers of Fel [19,20]. From an experimental point of view the systems of interest have been liquidcrystalline phases derived from bent-core or ferrocene-type molecules [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Influence of tetrahedral order on ferromagnetic gel phases

2019

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We investigate the macroscopic dynamics of gels with tetrahedral/octupolar symmetry, which possess in addition a spontaneous permanent magnetization. We derive the corresponding static and dynamic macroscopic equations for a phase, where the magnetization is parallel to one of the improper fourfold tetrahedral symmetry axes. Apart from elastic strains, we take into account relative rotations between the magnetization and the elastic network. The influence of tetrahedral order on these degrees of freedom is investigated and some experiments are proposed that are specific for such a material and allow to indirectly detect tetrahedral order. We also consider the case of a transient network and predict that stationary elastic shear stresses arise when a temperature gradient is applied.

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Selected Macroscopic Consequences of Tetrahedratic Order

Cited by 12 publications

References 29 publications

Tetrahedratic mesophases, chiral order, and helical domains induced by quadrupolar and octupolar interactions

Tetrahedratic mesophases, chiral order, and helical domains induced by quadrupolar and octupolar interactions

Macroscopic dynamics of polar nematic liquid crystals

Influence of tetrahedral order on ferromagnetic gel phases

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