Hysteresis Behavior of Texture in the Field-Induced Nematic-Cholesteric Relaxation

Abstract

The effects of bias voltages on the field-induced nematic-cholesteric relaxation are investigated both for samples with perpendicular boundaries and for ones with parallel boundaries, and are discussed in relation to the hysteresis behavior of texture. When the applied voltage is reduced from a value above the threshold to a bias voltage below the threshold a relaxation from the field-induced nematic to a Grandjean-like cholesteric state occurs, the relaxation time of which increases as the bias voltage approaches a certain value Vc↓; the ratio of Vc↓ to the threshold voltage Vc for cholesteric-to-nematic transition is about 0.5 irrespective of the boundary conditions. When the bias exceeds Vc↓, the transformation shows a hysteresis behavior such that the nematic state is kept for a long time until gradually replaced by focal conic domains nucleating from some local defect points; the boundary condition is found to play no essential role in the hysteresis behavior. An interpretation of the results is presented.