Experimental determination of the full Landau potential of bent-core doped ferroelectric liquid crystals

Abstract

The full Landau potential of a ferroelectric liquid crystal, doped with two different bent-core molecules at varying concentration, was determined experimentally. Using a multicurve fitting procedure, temperature and electric field dependent tilt angle and polarization measurements were analyzed according to the generalized Landau model of ferroelectric liquid crystals. From this analysis the three Landau coefficients as well as the polarization-tilt coupling parameters were obtained as a function of dopant concentration. It is shown that the two most varied parameters are those of the first Landau coefficient and the (chiral) linear polarization-tilt coupling constant. The results quantitatively verify the chiral induction capability of nonchiral bent-core shaped dopants and an observed increase in the electroclinic effect with increasing dopant concentration.