Cooling of an Antiferromagnet by Adiabatic Magnetization

Abstract
The heat capacity of powdered MnBr2·4H2O has been measured between 1.4° and 20°K in applied magnetic fields up to 24 kOe. The shift of the Néel point to lower temperatures with increasing field has been observed. A series of adiabatic magnetization measurements from initial temperatures above and below the zero field Néel point (TN(0)=2.13°K) has been carried out. For Ti<TN(0) the anticipated cooling effect is observed for applied fields smaller than that required to make the salt paramagnetic. Adiabatic data have been used to locate the curves of entropy vs temperature computed from the heat capacity relative to the curve for H=0.