Nuclear-Magnetic Susceptibility of SolidHe3: A Nuclear Antiferromagnet

Abstract

Measurements of the nuclear susceptibility of pure solid ${\mathrm{He}}^3$ from 0.4 to 0.04 °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 $\chi =\frac{c}{(T-\Theta )}$ with $\Theta =-1.5\mathrm{}\times {10}^{-3\mathrm{}}$ °K for a molar volume $v$ of 23.3 ${\mathrm{cm}}^3$/mole, $\Theta =-4\mathrm{}\times {10}^{-3\mathrm{}}$ °K for $v=23.6\mathrm{}$ ${\mathrm{cm}}^3$/mole, and $\Theta =-5.4\mathrm{}\times {10}^{-3\mathrm{}}$ °K for $v=24.2\mathrm{}$ ${\mathrm{cm}}^3$/mole. The negative values for $\Theta$ 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.