Apparent magnetization behavior of ferronematic liquid crystal based on sphere-like magnetic nanoparticles

Abstract

One prominent strategy for developing magnetically responsive liquid crystals (LCs) involves synthesizing LC ferrofluids. This study investigates the magnetization dynamics of ferronematic LCs (FNLCs) doped with sphere-like γ-Fe2O3 magnetic nanoparticles coated with oleic acid (MNPs). During the isotropic-to-nematic phase transition, the MNPs cluster into aggregates exhibiting anti-ferromagnetically coupled magnetic moments and adopting a rod-like structure with an aspect ratio of about 2, resulting in lower overall magnetization than the initial MNP powder. By modeling the FNLCs as a binary system composed of mono-dispersed and aggregated MNPs, our analysis reveals a significant reduction in saturation magnetization with increasing MNP concentration and aggregation. The FNLC cells with anti-parallel rubbed alignment layers exhibit enhanced rod-like aggregation, accompanied by a reduction in saturation magnetization.