Barre 12-22, 4e étage, pièce 426
Samo Kralj, professeur invité INSP
Condensed Matter Physics Department, Jožef Stefan Institute, Ljubljana, Slovenia
Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
Abstract
Topological defects (TDs) appear in all systems reached via a symmetry breaking phase transition and are consequently observed at all physical scales, including particle physics, condensed matter and even cosmology. Liquid crystals (LCs) are particularly adequate media to study TDs because they exhibit a rich variety of qualitatively different TDs and in them defects could be relatively easily experimentally observed, e.g., using polarizing microscopy. Of particular recent interest are the so-called twist disclinations in nematic LCs which do not carry the 3D topological charge, however, have nonzero 2D charge. Therefore, in 3D they are not topologically stable. Thus, in ordinary conditions they vanish soon after their creation. However, one can stabilize them energetically by imposing appropriate local orientational frustrations. In the lecture I will present basic properties of twist disclinations and general conditions via which they can be stabilized. Furthermore, I will demonstrate their importance from the perspective of basic physics (they might be analogues of the intriguing neutrinos in particle physics) and applications (they could be exploited as reconfigurable paths for controlled transport of appropriate nanoparticles).
