Magnetically induced Freedericksz transition and relaxation phenomena in nematic liquid crystals doped with azo-dyes

Abstract A static and dynamic investigation was performed on liquid crystal cells containing pure nematics and nematics doped with an azo-dye (Methyl Orange). It was found that the critical field for magnetic Freedericksz transition was decreased in samples containing the “ trans ” isomer and increased in those containing the “ cis ” isomer. Changes in the relaxation time τ A , τ B intervening when switching on/off the magnetic field were also noticed. A theoretical model was elaborated to explain these phenomena.