Cooling by Adiabatic Magnetization

Abstract

A new method to get reasonable cooling down to below 1°K using paramagnetic substances is discussed.
Preliminary experiment gave a promising aspect and encouraged us to develop the method. The idea is essentialy the same as that of Adiabatic Demagnetization. In some special substances, it is possible to increase amount of magnetic entropy by applying external magnetic field. Magnetic cooling can, in such cases, be followed by adiabatic magnetization process which is just contrary to adiabatic demagnetization. One of the substances used in the experiment, is Cu(NO₃)₂⋅2.5H₂O. Starting from T_i=1.6°K in the course of adiabatic magnetization, the lowest T_f=0.5°K was reached at 36kG where the entropy maximum was expected.