Phase synchronization of the hydrodynamic and orientational modes during electroconvection in a nematic liquid crystal

The spatiotemporal dynamics of oscillating electroconvective structures appearing in a nematic liquid crystal (NLC) under the combined action of applied alternating (ac) and direct (dc) electric voltages has been experimentally studied. It is established that an increase in the dc component of the applied voltage leads to synchronization of the hydrodynamic mode with the orientational twist mode of the NLC director. The synchronization parameter and the phase shift of the modes are determined as function of the applied dc voltage. The results confirm the flexoelectric mechanism of synchronization.