Determination of the Landau potential of chiral enantiomer ferroelectric liquid crystal mixtures

The full Landau potential was determined for mixtures of the two chiral configurations of ferroelectric liquid crystal enantiomers. Experimental temperature and electric field dependent tilt and polarisation data are analysed via a multi-curve fitting procedure to determine all the parameters of the generalised Landau model for ferroelectric liquid crystals. The three Landau coefficients alpha, b and c as well as the bilinear coupling, C, biquadratic coupling, Omega and dielectric susceptibility, chi(0), were obtained as a function of enantiomeric excess. The chirality dependent bilinear coupling term vanishes as the chirality of the system tends to zero on approaching the racemic mixture. All other terms remain constant within the limits of error, providing experimental evidence that the bilinear coupling term is the only chirality dependent term of the generalised Landau model.