Előadó: Robin Selinger (Kent State University (vendéglátó: Salamon Péter))
Előadás címe: Frank-Read sources in nematic liquid crystals: engineered mechanism for heterogeneous defect nucleation
Helyszín: 1-es épület Tanácsterem, illetve online: https://wigner-hu.zoom.us/j/87329092467?pwd=NlRKWUQ4cks2K3Ara3c5V3BCOC9… Meeting ID: 873 2909 2467 Passcode: 174961
Dátum: 2022. július 7., 10:00
Összefoglaló:
The Frank-Read (F-R) source, a well-studied concept in metallurgy, is a mechanism by which dislocation loops are emitted via repeated heterogeneous nucleation, giving rise to ductility in crystalline solids. We demonstrate that the same fundamental mechanism enables multiplication of disclination loops in nematic liquid crystals under shear. And while F-R sources form randomly in deformed crystals e.g. through dislocation pinning by impurities, by contrast we can precisely engineer F-R sources in a nematic liquid crystal cell by inscribing anchoring patterns on the confining substrates. We discuss possible applications in passive and active nematics.
Előadó: Jonathan Selinger (Kent State University (vendéglátó: Salamon Péter))
Előadás címe: Geometry and Mechanics of Disclinations in Nematic Liquid Crystals
Helyszín: 1-es épület Tanácsterem, illetve online: https://wigner-hu.zoom.us/j/87329092467?pwd=NlRKWUQ4cks2K3Ara3c5V3BCOC9… Meeting ID: 873 2909 2467 Passcode: 174961
Dátum: 2022. július 7., 10:30
Összefoglaló:
In this talk, we present recent progress in understanding topological defects in liquid crystals, both conventional and active. We emphasize that topology is only one part of the theory of topological defects. Beyond topology, we need geometry to characterize the orientational properties of defects. We need energy and forces to understand the interactions between defects, and the conventional and active stimuli acting on them. Further, we need dynamics to understand the motion of defects under these forces, in the presence of dissipation. We discuss all of these aspects of the theory of defects in both two and three dimensions.
