Magnetization Cooling and Magnetosolidification ofHe3

A spin-wave calculation of the thermodynamic properties of antiferromagnetically ordered solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in a magnetic field has been carried out. A cooling effect with isentropic magnetization is predicted for fields near the ($T=0\mathrm{}$) critical value $H_c=\frac{2zJI}{{\gamma }_n\hslash } \left(\cong 74 \mathrm{kG}\right)$. In a second calculation a field $H\sim H_c$ is found to displace the melting curve $P\left(T\right)\mathrm{}$ to significantly lower pressures; it follows that a two-phase mixture of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ can be isentropically solidified (and thus cooled) by application of a field from starting temperatures $T\sim 5$ mdeg K as a useful adjunct to the Pomeranchuk cooling method.