Nuclear-Magnetic Susceptibility of SolidHe3: A Nuclear Antiferromagnet

Measurements of the nuclear susceptibility of pure solid ${\mathrm{He}}^{3}$ from 0.4 to 0.04 \ifmmode^\circ\else\textdegree\fi{}K are described. The ${\mathrm{He}}^{4}$ content of the sample was less than 10 ppm. The susceptibility is shown to obey a Curie-Weiss law $\ensuremath{\chi}=\frac{c}{(T\ensuremath{-}\ensuremath{\Theta})}$ with $\ensuremath{\Theta}=\ensuremath{-}1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ \ifmmode^\circ\else\textdegree\fi{}K for a molar volume $v$ of 23.3 ${\mathrm{cm}}^{3}$/mole, $\ensuremath{\Theta}=\ensuremath{-}4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ \ifmmode^\circ\else\textdegree\fi{}K for $v=23.6$ ${\mathrm{cm}}^{3}$/mole, and $\ensuremath{\Theta}=\ensuremath{-}5.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ \ifmmode^\circ\else\textdegree\fi{}K for $v=24.2$ ${\mathrm{cm}}^{3}$/mole. The negative values for $\ensuremath{\Theta}$ mean that solid ${\mathrm{He}}^{3}$ nuclei should order antiferromagnetically at very low temperatures and low magnetic fields. The experimental data are compared with current theories and other experiments.