Magnetic refrigeration is a cooling technology based on the magnetocaloric effect. This technique can be used to attain extremely low temperatures (well below 1 kelvin ), as well as the ranges used in common refrigerators , depending on the design of the system.
The fundamental principle was suggested by Debye (1926) and Giauque (1927), and the first working magnetic refrigerators were constructed by several groups beginning in 1933. Magnetic refrigeration was the first method developed for cooling below about 0.3 kelvin (a temperature attainable by 3He / 4He dilution refrigeration ).
"Magnetic refrigeration based on the magnetocaloric effect (MCE) has been proposed as an attractive alternative to gas compression technology.
Some calculations suggest that MCE can be obtained with higher efficiencies than compressor driven refrigeration.
We examine the MCE in a system of nickel ferrite nanoparticles with size range of 6 to 15 nm. A peak in the MCE at 55 K is observed that increases with higher magnetic fields. This gives this system a relatively high peak entropy change compared to other ferrite systems.
A sensitive radio-frequency (RF) transverse susceptibility measurement has also been used to study the magnetic anisotropy. We show that the MCE peak is not associated with the blocking temperature and is likely a field-driven surface spin reorientation which also has a signature in the transverse susceptibility."
Magnetic anisotropy and magnetocaloric effect (MCE) in NiFe2O4 nanoparticles, Author(s): J. Gass, N. A. Frey, M. B. Morales, M. J. Miner, S. Srinath, H. Srikanth
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