Abstract
We studied the structural transitions in ferronematics based on the thermotropic nematic liquid crystal MBBA (4′ -methoxybenzylidene-4-n-butylaniline) having a nematic-to-isotropic transition temperature T N–I = 48.0○C and in MBBA-based ferronematics doped with a magnetic suspension consisting of Fe3O4 particles (10 nm in diameter) coated with oleic acid as a surfactant. The ferronematic samples were prepared with different volume concentrations of magnetic particles φ =,1× 10−4, 2× 10−4 and 5×10−4. The temperature dependences of the critical magnetic fields in a bias electric field under strong applied magnetic fields are presented. We calculated the surface density of anchoring energy W at the nematic–magnetic particle boundary. Scaling of the structural transition in the MBBA and MBBA-based ferronematics with the temperature of the nematic-to-isotropic transition was observed.
Acknowledgements
This work was supported by the Grant Agency VEGA under grant No. 6166 and by the Science and Technology Assistance Agency APVT under contract No. 51-027904.