Ferrofluids consist of ferromagnetic nanoparticles suspended in a fluid. When subjected to strong magnetic fields, they develop a distinctive peak-and-valley formation due to the normal-field instability. The shape is a result of minimizing the magnetic energy of the fluid. Both gravity and surface tension resist the formation of these peaks. Ferrofluids, in addition to appearing in art exhibits, can be used as liquid seals, MRI contrast agents, and loudspeaker cooling fluids. (Photo credit: Maurizio Mucciola)
Spiky Ferrofluid
