Seminarium Fizyki Materii Skondensowanej

In this talk I will discuss the physics of nematic electrolytes: ions in nematic liquid crystals. Liquid crystals can flow like ordinary liquids, but there are also differences, such as the emergence of elasticity. Nematics can be seen as orientationally ordered anisotropic dielectrics that are flexoelectric - they can form a spontaneous polarisation upon straining the material which is not accounted for in the dielectric tensor. When convoluted with the ionic degrees of freedom, several interesting phenomena can occur. I will demonstrate that nematic electrolytes in some cases can be characterized by an anisotropic Debye screening length and how topological defects can become charged and/or cause ionic charge separation around them forming ionic multilayers (instead of the familiar double layers). Furthermore, the topological defects can alter the surface charge distribution of mesoscopic objects such as flat plates or spheres and alter the differential capacitance depending on its global orientation. Finally, I will discuss our recent work on the charge dynamics of a nematic electrolyte, which in a sense have many similarities with that of an Archimedes' screw: a hydraulic machine that can either pump or generate energy as a turbine. This leads to a coupling of the charge current to the winding density of a liquid crystal, which naturally leads to topological defects being driven by ionic current or being used as inductors.