We show the strong effect of chirality on the interparticle force in the chiral nematic liquid crystals. The observed force is attractive, but there are numbers of metastable states at the distances which are multiple of the liquid crystal pitch. By increasing the chirality of the liquid crystal, the number of metastable states is increased, while the interparticle force is decreased. At small separation the defect lines of particles are entangled and the stable dimer is formed.
COBISS.SI-ID: 26714151
In collaboration with Notre dame University, Indiana, thin flakes of MoS2 synthesized at JSI, have been used for fabrication of field effect transistors. We have found the transistor characteristics undistinguishable from that of mechanically exfoliated MoS2 single crystals; the on/off current ratio was 105 and the transistor behavior of n-type. The advantages of multilayer MoS2 flakes as channel material with respect to MoS2 monolayers are in easier way of the synthesis and manipulation, in lower interaction with substrate, and in better chemical stability.
COBISS.SI-ID: 26518311
We demonstrate a new class of soft matter optical fibers, which are self-assembled in a form of microtubes grown in an aqueous surfactant dispersion of a smectic-A liquid crystal. The diameter of the fibers is highly uniform and the fibers are highly birefringent. We demonstrate guiding of light along the fiber and Whispering Gallery Mode lasing in a plane perpendicular to the fiber. The smectic-A fibers are soft and flexible and can be manipulated with laser tweezers demonstrating a promising approach for realization of soft photonic circuits.
COBISS.SI-ID: 27532583
We use numerical modeling to study the flow patterns of an active nematic confined in a cylindrical capillary, considering both planar and homeotropic boundary conditions. We find that active flow emerges not only along the capillary axis but also within the plane of the capillary, where radial vortices are formed. If topological defects are imposed by the boundary conditions, they act as local pumps driving the flow. At higher activity, we demonstrate escape of the active defects and flow into the third dimension, indicating the importance of dimensionality in active materials. We argue that measuring the magnitude of the active flow as a function of the capillary radius allows determination of a value for the activity coefficient.
COBISS.SI-ID: 2528100
First 3D nematic dipolar colloidal crystal was presented, which is a new milestone in the field of assembling nematic colloids. It was predicted by Landu- de Gennes analysis of stability colloidal crystal structures, assembled with the help of laser tweezers and studied by 3D confocal polarization fluorescent microscopy. Dipolar colloidal crystal has tetragonal symmetry and exhibit giant electrostriction. An external electric field induces a reversible and controllable electro-rotation of the crystal as a whole, when using LC with negative dielectric anisotropy.
COBISS.SI-ID: 26543143