Nonlinear dynamics and kinetics of Freedericksz transitions in nematic liquid crystals

Strongly nonlinear orientational vibrations of a nematic liquid crystal in a destabilizing magnetic field are considered. Freedericksz transitions between the left- and right-twisted structural states are analyzed. Dispersion equations relating the average oscillation frequencies to the strength of the constant magnetic field, layer thickness, and material constants are derived with and without allowance for dissipation. Pulsating oscillation regimes with constant amplitude (but decreasing frequency) in the presence of strong dissipation (due to rotational viscosity) are revealed; they are driven by a magnetic field that exponentially decreases over time.