Ferrofluid

Description

The ferromagnetic nano-particles are coated with a surfucat  to prevent their agglomeration (due to  and magnetic forces). Although the name may suggest otherwise, ferrofluids do not display ferromagnetizm , since they do not retain magnetisation in the absence of an externally applied field. In fact, ferrofluids display paramagnetism , and are often referred as being "superparamagnetic" due to their large magnetitc suspensionities.