Electric-field-induced local rotation of molecules in nematic-cholesteric droplets

The structural dynamics of nematic-cholesteric liquid crystal (LC) droplets occurring in an isotropic environment in an alternating electric field have been studied. It is established that, above a certain threshold field strength, the conoscopic pattern of a Maltese cross becomes dynamic and begins to rotate. The threshold voltage, as well as the frequency of rotation, is almost independent of the droplet diameter. This phenomenon is related to the development of a self-consistent rotation of LC molecules in the plane perpendicular to the droplet axis. It is shown that this rotation initiates the propagation of a helicoidal wave from one pole of the droplet to another.