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In twist-bend nematic (N\textsubscript{TB}) liquid crystals (LCs), the mean molecular orientation exhibits heliconical structure with nanoscale periodicity. On the mesoscopic scale, N\textsubscript{TB} resembles layered systems (like…

Soft Condensed Matter · Physics 2020-11-25 M. Praveen Kumar , P. Kula , Surajit Dhara

We report a dynamic light scattering study of the fluctuation modes in a thermotropic liquid crystalline mixture of monomer and dimer compounds that exhibits the twist-bend nematic ($\mathrm{N_{TB}}$) phase. The results reveal a spectrum of…

The nematic twist-bend ($\mathrm{N_{TB}}$) phase, exhibited by certain thermotropic liquid crystalline (LC) dimers, represents a new orientationally ordered mesophase -- the first distinct nematic variant discovered in many years. The…

The twist-bend nematic phase, $N_{\rm TB}$, may be viewed as a heliconical molecular arrangement in which the director $\bf n$ precesses uniformly about an extra director field, $\bf t$. It corresponds to a nematic ground state exhibiting…

The twist-bend nematic (Ntb) phase is a recent addition to the nematic (N) phases of liquid crystals (LCs). A net polar order in the Ntb phase under an external electric field was predicted in several recent theoretical studies but yet to…

Soft Condensed Matter · Physics 2022-09-13 Sourav Patranabish , Aloka Sinha , Madhu B. Kanakala , Channabasaveshwar V. Yelamaggad

The understanding of self-organization in the twist-bend nematic $(N_\text{TB})$ phase, identified in 2011 in liquid crystal dimers, is at the forefront of soft matter research worldwide. This new nematic phase develops structural chirality…

Soft Condensed Matter · Physics 2020-10-27 Lech Longa , Wojciech Tomczyk

The extended Frank elastic energy density is used to investigate the existence of a stable periodically modulate structure that appears as a ground state exhibiting a twist-bend molecular arrangement. For an unbounded sample, we show that…

Soft Condensed Matter · Physics 2017-06-01 M. P. Rosseto , R. R. Ribeiro de Almeida , R. S. Zola , G. Barbero , I. Lelidis , L. R. Evangelista

A dynamic light scattering study of director-layer fluctuations in the antiferroelectric smectic-ZA phase of the ferroelectric nematic liquid crystal DIO is reported. The dynamics are consistent with the distinctive feature of the ZA phase…

We present a comprehensive set of measurements of optical, dielectric, diamagnetic, elastic and viscous properties in the nematic (N) phase formed by a liquid crystalline dimer. The studied dimer, 1,7-bis-4-(4-cyanobiphenyl) heptane…

The nonlinear elastic properties of nematic liquid crystals have acquired new interest with the recent experimental observation of bulk modulated nematic phases which are composed by achiral molecules. We extend the Oseen-Zocher-Frank's…

Soft Condensed Matter · Physics 2018-11-09 I. Lelidis , G. Barbero

X-ray scattering and polarized microscopic studies of the structure and order parameters in the nematic (N) and heliconical, or the twist-bend nematic (Ntb), phase have been performed as a function of temperature. The nematic orientational…

We study the flow behaviour of a twist-bend nematic $(N_{TB})$ liquid crystal. It shows three distinct shear stress ($\sigma$) responses in a certain range of temperatures and shear rates ($\dot{\gamma}$). In Region-I,…

Soft Condensed Matter · Physics 2021-08-02 M. Praveen Kumar , Jakub Karcz , Przemyslaw Kula , Surajit Dhara

Resonant x-ray scattering shows that the bulk structure of the twist-bend liquid crystal phase, recently discovered in bent molecular dimers, has spatial periodicity without electron density modulation, indicating a lattice-free heliconical…

Elastic constants of splay K_11, twist K_22, and bend K_33 of nematic liquid crystals are often assumed to be equal to each other in order to simplify the theoretical description of complex director fields. Here we present examples of how…

Soft Condensed Matter · Physics 2024-03-19 Oleg D. Lavrentovich

We review the physics underlying Meyer's conjecture of how macroscopic-scale twist and bend conspire within the Frank-Oseen elasticity theory of nematics to create a heliconical arrangement of the uniaxial, apolar nematic director, the…

Soft Condensed Matter · Physics 2020-09-25 Edward T. Samulski , Alexandros G. Vanakaras , Demetri J. Photinos

Dielectric spectroscopy of a twist bend nematic phase of an achiral bent core liquid crystalline compound under DC bias is used to investigate its response to electric field. Two collective relaxation processes are revealed, these are…

Soft Condensed Matter · Physics 2018-09-12 K. Merkel , A. Kocot , J. K. Vij , G. Shanker

The dielectric spectra of the twist bend nematic phase of the bent shaped achiral liquid crystal dimer are studied for the determination of the different relaxation modes. The two molecular processes were assigned one to the precessional…

Applied Physics · Physics 2020-01-08 K. Merkel , A. Kocot , C. Welch , G. H. Mehl

The twist-bend nematic liquid crystal phase is a three-dimensional fluid in which achiral bent molecules spontaneously form an orientationally ordered macroscopically chiral heliconical winding of molecular scale pitch, in absence of…

The ground state of twist-bend nematic liquid crystals is a heliconical molecular arrangement in which the nematic director precesses uniformly about an axis, making a fixed angle with it. Both precession senses are allowed in the ground…

Soft Condensed Matter · Physics 2014-04-15 Epifanio G. Virga

The recently discovered twist-bend nematic phase, $\rm N_{tb}$, is a non-uniform equilibrium nematic phase that presents a spontaneous bend with a precession of the nematic director, $\textbf{n}$, on a conical helix with a tilt angle…

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