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University of Stuttgart (Germany), 02 November: The first experimental demonstration of magnetic refrigeration of a gas is reported in the November issue of Nature Physics. Magnetic refrigeration has been used since the 1930s to cool solid samples. Marco Fattori and colleagues now present evidence suggesting that the ‘new old’ method might also be a valuable tool for producing gases close to zero absolute temperature.

Magnetic refrigeration, also known as adiabatic demagnetization cooling, works by exposing suitable materials to a changing magnetic field. The process converts kinetic energy into magnetic energy, leading to a drop in temperature. In a solid, this typically involves lattice vibrations; in a gas, however, the coupling between the spin of the constituent particles- responsible for magnetism- and their motion is generally too weak to allow cooling to occur.

In the current study the authors show that in a gas made of chromium-52 atoms a coupling exists that is strong enough to allow efficient magnetic refrigeration. Researchers propose that a much broader class of gases might be amenable to adiabatic demagnetization cooling, and expect that the method could become a useful way to reach temperatures near absolute zero in gases- a temperature range that offers a rich assortment of exotic phenomena for physicists to explore.

(ResearchSEA)