scholarly journals Topological Defect Arrays in Nematic Liquid Crystals Assisted by Polymeric Pillar Arrays: Effect of the Geometry of Pillars

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 314 ◽  
Author(s):  
MinSu Kim ◽  
Francesca Serra
Keyword(s):  
Liquid Crystals ◽  
Topological Defect ◽  
Condensed Matter ◽  
Topological Defects ◽  
Spatial Arrangement ◽  
Photonic Devices ◽  
Elastic Response ◽  
Structured Fluids ◽  
Pillar Arrays

Topological defects that spontaneously occur in condensed matter and structured fluids such as liquid crystals are useful for their elastic and optical properties, but often the applicability of defect arrays to optics and photonic devices relies on the regularity and tunability of the system. In our recent work [Adv. Opt. Mater. 8, 1900991 (2020)], we showed the formation of regular, reconfigurable, and scalable patterns by exploiting the elastic response of a defect array in liquid crystals in the presence of a polymeric pillar array. In this work, we experimentally investigate the role of size and shape of the pillars on the defect array. We find that the pillar size and geometry provide additional means to regulate the response time, the threshold voltage for the defects’ formation, and the spatial arrangement of the defects.

scholarly journals Emergence of dynamic vortex glasses in disordered polar active fluids

2021 ◽  
Vol 118 (10) ◽  
pp. e2018218118
Author(s):  
Amélie Chardac ◽  
Suraj Shankar ◽  
M. Cristina Marchetti ◽  
Denis Bartolo
Keyword(s):  
Liquid Crystals ◽  
Heterogeneous Media ◽  
Broad Class ◽  
Condensed Matter ◽  
Topological Defects ◽  
Living Cells ◽  
Quenched Disorder ◽  
Active Matter ◽  
Far From Equilibrium ◽  
Topological Singularities

In equilibrium, disorder conspires with topological defects to redefine the ordered states of matter in systems as diverse as crystals, superconductors, and liquid crystals. Far from equilibrium, however, the consequences of quenched disorder on active condensed matter remain virtually uncharted. Here, we reveal a state of strongly disordered active matter with no counterparts in equilibrium: a dynamical vortex glass. Combining microfluidic experiments and theory, we show how colloidal flocks collectively cruise through disordered environments without relaxing the topological singularities of their flows. The resulting state is highly dynamical but the flow patterns, shaped by a finite density of frozen vortices, are stationary and exponentially degenerated. Quenched isotropic disorder acts as a random gauge field turning active liquids into dynamical vortex glasses. We argue that this robust mechanism should shape the collective dynamics of a broad class of disordered active matter, from synthetic active nematics to collections of living cells exploring heterogeneous media.

Spontaneous emission in inertial and dissipative nematic liquid crystals: the role of critical phenomena

2021 ◽  
Author(s):  
José Henrique do Nascimento ◽  
Felipe Arruda Pinheiro ◽  
Marcello Barbosa Silva Neto
Keyword(s):  
Liquid Crystals ◽  
Critical Phenomena ◽  
Spontaneous Emission ◽  
First Principles ◽  
Nematic Phase ◽  
Nematic Liquid Crystals ◽  
Photonic Devices ◽  
Light Sources ◽  
Nematic Director

Abstract We develop a rigorous, field-theoretical approach to the study of spontaneous emission in inertialand dissipative nematic liquid crystals, disclosing an alternative application of the massive Stueck-elberg gauge theory to describe critical phenomena in these systems. This approach allows one notonly to unveil the role of phase transitions in the spontaneous emission in liquid crystals but also to make quantitative predictions for quantum emission in realistic nematics of current scientific andtechnological interest in the field of metamaterials. Specifically, we predict that one can switchon and off quantum emission in liquid crystals by varying the temperature in the vicinities of thecrystalline-to-nematic phase transition, for both the inertial and dissipative cases. We also predictfrom first principles the value of the critical exponent that characterizes such a transition, whichwe show not only to be independent of the inertial or dissipative dynamics, but also to be in goodagreement with experiments. We determine the orientation of the dipole moment of the emitterrelative to the nematic director that inhibits spontaneous emission, paving the way to achieve direc-tionality of the emitted radiation, a result that could be applied in tuneable photonic devices suchas metasurfaces and tuneable light sources.

scholarly journals Nematic colloids, topology and photonics

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120266 ◽  
Author(s):  
I. Muševič
Keyword(s):  
Liquid Crystals ◽  
Recent Progress ◽  
Colloidal Particles ◽  
Topological Defects ◽  
Chiral Nematic

We review and discuss recent progress in the field of nematic colloids, with an emphasis on possible future applications in photonics. The role of the topology is described, based on experimental manipulations of the topological defects in nematic colloids. The topology of the ordering field in nematics provides the forces between colloidal particles that are unique to these materials. We also discuss recent progress in the new field of active microphotonic devices based on liquid crystals (LCs), where chiral nematic microlasers and tuneable nematic microresonators are just two of the recently discovered examples. We conclude that the combination of topology and microphotonic devices based on LCs provides an interesting platform for future progress in the field of LCs.

scholarly journals Anomalous transport due to Weyl fermions in the chiral antiferromagnets Mn3X, X = Sn, Ge

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Taishi Chen ◽  
Takahiro Tomita ◽  
Susumu Minami ◽  
Mingxuan Fu ◽  
Takashi Koretsune ◽  
...  
Keyword(s):  
Technological Innovation ◽  
Essential Role ◽  
Condensed Matter ◽  
Zero Field ◽  
Theoretical Studies ◽  
Planar Hall Effect ◽  
Topological States ◽  
Experimental And Theoretical Studies ◽  
Weyl Fermions

AbstractThe recent discoveries of strikingly large zero-field Hall and Nernst effects in antiferromagnets Mn3X (X = Sn, Ge) have brought the study of magnetic topological states to the forefront of condensed matter research and technological innovation. These effects are considered fingerprints of Weyl nodes residing near the Fermi energy, promoting Mn3X (X = Sn, Ge) as a fascinating platform to explore the elusive magnetic Weyl fermions. In this review, we provide recent updates on the insights drawn from experimental and theoretical studies of Mn3X (X = Sn, Ge) by combining previous reports with our new, comprehensive set of transport measurements of high-quality Mn3Sn and Mn3Ge single crystals. In particular, we report magnetotransport signatures specific to chiral anomalies in Mn3Ge and planar Hall effect in Mn3Sn, which have not yet been found in earlier studies. The results summarized here indicate the essential role of magnetic Weyl fermions in producing the large transverse responses in the absence of magnetization.

scholarly journals Properties of twisted topological defects in 2D nematic liquid crystals

Soft Matter ◽  
2021 ◽  
Author(s):  
Daniel Pearce ◽  
Karsten Kruse
Keyword(s):  
Liquid Crystals ◽  
Nematic Liquid Crystals ◽  
Topological Defects ◽  
Two Dimensional

Topological defects are one of the most conspicuous features of liquid crystals. In two dimensional nematics, they have been shown to behave effectively as particles with both, charge and orientation,...

scholarly journals A Review on Metamaterials for Device Applications

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 518
Author(s):  
N. Suresh Kumar ◽  
K. Chandra Babu Naidu ◽  
Prasun Banerjee ◽  
T. Anil Babu ◽  
B. Venkata Shiva Reddy
Keyword(s):  
Quantum Interference ◽  
Effective Properties ◽  
Photonic Devices ◽  
Vital Role ◽  
Major Type ◽  
Electric Permittivity ◽  
Superconducting Quantum Interference Devices ◽  
Device Applications ◽  
Microwave Sensors

Metamaterials are the major type of artificially engineered materials which exhibit naturally unobtainable properties according to how their microarchitectures are engineered. Owing to their unique and controllable effective properties, including electric permittivity and magnetic permeability, the metamaterials play a vital role in the development of meta-devices. Therefore, the recent research has mainly focused on shifting towards achieving tunable, switchable, nonlinear, and sensing functionalities. In this review, we summarize the recent progress in terahertz, microwave electromagnetic, and photonic metamaterials, and their applications. The review also encompasses the role of metamaterials in the advancement of microwave sensors, photonic devices, antennas, energy harvesting, and superconducting quantum interference devices (SQUIDs).

Light propagation in cholesteric liquid crystals: the role of chirality

2020 ◽  
Vol 713 (1) ◽  
pp. 65-77
Author(s):  
Tianyi Guo ◽  
Xiaoyu Zheng ◽  
Peter Palffy-Muhoray
Keyword(s):  
Liquid Crystals ◽  
Light Propagation ◽  
Cholesteric Liquid Crystals

Virtual trabecular bone models and their mechanical response

2008 ◽  
Vol 222 (8) ◽  
pp. 1185-1195 ◽  
Author(s):  
F E Donaldson ◽  
P Pankaj ◽  
A H Law ◽  
A H Simpson
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Response ◽  
Anatomical Site ◽  
Virtual Samples ◽  
Micro Level ◽  
Architectural Characteristics

The study of the mechanical behaviour of trabecular bone has extensively employed micro-level finite element (μFE) models generated from images of real bone samples. It is now recognized that the key determinants of the mechanical behaviour of bone are related to its micro-architecture. The key indices of micro-architecture, in turn, depend on factors such as age, anatomical site, sex, and degree of osteoporosis. In practice, it is difficult to acquire sufficient samples that encompass these variations. In this preliminary study, a method of generating virtual finite element (FE) samples of trabecular bone is considered. Virtual samples, calibrated to satisfy some of the key micro-architectural characteristics, are generated computationally. The apparent level elastic and post-elastic mechanical behaviour of the generated samples is examined: the elastic mechanical response of these samples is found to compare well with natural trabecular bone studies conducted by previous investigators; the post-elastic response of virtual samples shows that material non-linearities have a much greater effect in comparison with geometrical non-linearity for the bone densities considered. Similar behaviour has been reported by previous studies conducted on real trabecular bone. It is concluded that virtual modelling presents a potentially valuable tool in the study of the mechanical behaviour of trabecular bone and the role of its micro-architecture.

Sign in / Sign up

Export Citation Format

Share Document