Magnetic field induced Fréedericksz transition in a system of ultrafine spherical [formula omitted] nanoparticles doped 7CB media

Abstract

In this work, experimental studies of electrically and magnetically induced re-orientational transitions in suspensions of cobalt ferrite (CoFe2O4) nanoparticles in 7CB (4-n-heptyl-4'-cyanobiphenyl) liquid crystal (LC) are presented. Two concentrations are studied (i.e 0.033wt% or sample A and 0.044wt% or sample B). The results obtained are compared with the pristine liquid crystal. Low threshold voltages and magnetic fields for the re-orientational transition are observed in the doped cases. The nanoparticles bonded to the LC in close proximity are orienting in a parallel manner with the bulk liquid crystal media and causing these changes. Effect of the polarity and position of the magnet on the re-orientational mechanism in comparison to the pristine sample is also studied.