Editing Magnetocaloric effect (section)

=== Nuclear demagnetization ===

One variant of adiabatic demagnetization that continues to find substantial research application is nuclear demagnetization refrigeration (NDR).  NDR follows the same principles, but in this case the cooling power arises from the [[Spin (physics)#Magnetic moments|magnetic dipoles of the nuclei]] of the refrigerant atoms, rather than their electron configurations.  Since these dipoles are of much smaller magnitude, they are less prone to self-alignment and have lower intrinsic minimum fields.  This allows NDR to cool the nuclear spin system to very low temperatures, often 1 μK or below. Unfortunately, the small magnitudes of nuclear magnetic dipoles also makes them less inclined to align to external fields.  Magnetic fields of 3 teslas or greater are often needed for the initial magnetization step of NDR.

In NDR systems, the initial heat sink must sit at very low temperatures (10–100 mK).  This precooling is often provided by the mixing chamber of a dilution refrigerator<ref>{{Cite journal | doi = 10.1016/j.cryogenics.2021.103390| issn=0011-2275| title = Development of Dilution refrigerators – A review | journal = Cryogenics| volume = 121| year = 2022| last1 = Zu | first1 = H.| last2 = Dai | first2 = W.| last3 = de Waele | first3 = A.T.A.M.| s2cid=244005391}}</ref> or a paramagnetic salt.