Faraday rotation in ligand capped Fe3O4 nanoparticles – Experimental investigations for single scattering model

Magnetite (Fe3O4) nanoparticles capped with oleic acid and oleylamine were prepared by wet-chemical method. Faraday rotation on the synthesized Fe3O4 nanoparticles were measured as a function of magnetic field strength and concentration. The magnitude of the three components of the dielectric tensor of the Fe3O4 nanoparticle were obtained based on single-scattering model. These are Im∊xy=5.2×10-4,Im∊xx/yy=-0.07, and Im∊zz=-0.32. Besides, we found that Faraday rotation data obtained show two distinct features when compared to the data reported in the literature. The distinct features are 1) saturation in Faraday rotation with magnetic field strength, and 2) negligible concentration dependence. More importantly, our samples did not follow chain formation like other samples reported in the literature. These observations can be attributed to a stable colloid without any aggregation in our samples as a result of sample preparation method. In samples reported in the literature although they are stable these suffer from aggregation which can lead to the formation of chains easily than in our samples.