STUDY OF MAGNETIC FREDERICKSZ TRANSITION IN FERRONEMATICS

The magnetic Fredericksz transition in ferronematics (thermotropic nem atic liquid crystals 7CB and MBBA combined with fine magnetic particle s of a size 10 nm) as a function of concentration of magnetic particle s was studied by using simple dielectric measurements. The increase of the threshold magnetic field is observed in 7CB based ferronematic wh ile the decrease of threshold field in MBBA based ferronematic is obse rved when the concentration of magnetic particles is increased. Experi mental results are discussed in the framework of Brochard, de Gennes a nd Burylov, Raikher theories.