This is at the limit for conventional magnetic recording that was predicted in 1999. Future hard disk technologies currently in development include: heat-assisted magnetic recording (HAMR) and microwave-assisted magnetic recording (MAMR), which use materials that are stable at much smaller sizes. They require localized heating or microwave excitation before the magnetic orientation of a bit can be changed. Bit-patterned recording (BPR) avoids the use of fine-grained media and is another possibility. In addition, magnetic recording technologies based on topological distortions of the magnetization, known as skyrmions, have been proposed. Applications General applications Ferrofluid: tunable viscosity Biomedical applications Imaging: contrast agents in magnetic resonance imaging (MRI) Magnetic separation: cell-, DNA-, protein- separation, RNA fishing Treatments: targeted drug delivery, magnetic hyperthermia, magnetofection See also Iron oxide nanoparticles Single-molecule magnet References Notes Sources An English translation is available in External links Superparamagnetism of Co-Ferrite Nanoparticles Powerpoint presentation on Superparamagnetism in pdf Magnetic ordering Statistical mechanics