The year 1926 was a remarkable year for low-temperature physics and technology. H. Kamerlingh Onnes reached 0.7 K by pumping on his liquid 4He bath with an enormous battery of pumps. Realizing that there would be no element with a lower boiling point than helium, he predicted that the temperature of 0.7 K would remain the minimum temperature achievable by mankind in the laboratory unless somebody discovered a completely new refrigeration technology that did not depend on the latent heat of evaporation. (Of course, he was not aware that there exists a lighter helium isotope, 3He, which pushes this limit down by about a factor of three). In the same year this completely new refrigeration technology was proposed. P. Debye and W.F. Giauque independently made the proposal that lower temperatures could be reached by using the magnetic disorder entropy of electronic magnetic moments in paramagnetic salts, a method later called adiabatic demagnetization of paramagnetic salts. Not until seven years later, in 1933, was this proposal converted into a practical realization, when W.F. Giauque and D.P. MacDougall (Berkeley) reached 0.53 K, and a little later W.J. de Haas, E.C. Wiersma and H.A. Kramers (Leiden) reached 0.27 K. In fact, this was the first important low-temperature experiment since the end of the 19th century in which the University in Leiden was not the first to achieve success (for this early work see the relevant references in [9.1–3]).
CITATION STYLE
Pobell, F. (1992). Refrigeration by Adiabatic Demagnetization of a Paramagnetic Salt. In Matter and Methods at Low Temperatures (pp. 148–157). Springer Berlin Heidelberg. https://doi.org/10.1007/978-3-662-08578-3_9
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