Magnetic Field Induced Structural Transitions in 6CHBT-Based Ferronematics

Ferronematics are stable colloidal suspensions of magnetic particles in nematic liquid crystals. The presence of the magnetic particles enhances the magnetic susceptibility of ferronematics, in comparison with pure liquid crystals. In this work the thermotropic liquid crystal 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanato-benzene (6CHBT) and 6CHBT dissolved in phenyl isothiocyanate were doped with spherical magnetic nanoparticles with aim to increase the sensitivity of the liquid crystal on an external magnetic field. The volume concentration of the magnetic particles was 5 × $10^{-4}$. The phase transition temperature from isotropic to nematic phase in the external magnetic field up to 12 T was monitored by precise capacitance measurements in the capacitance cells filled with nematic sample as well as with the prepared ferronematic sample. There was no observable shift in the transition temperature in the case of pure 6CHBT, 6CHBT doped with spherical particles and 6CHBT dissolved in phenyl isothiocyanate while in the case of 6CHBT dissolved in phenyl isothiocyanate doped with spherical magnetic particles the shift in the temperature about 9C of the phase transition from isotropic to droplet state at the external magnetic field 12 T was observed.