Magnetic Susceptibility ofHe3in Grafoil at Ultralow Temperatures

Measurements of the NMR susceptibility of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in Grafoil indicate that the surface layer exhibits a Curie-Weiss magnetization tending towards ferromagnetism. The surface magnetization has a magnitude approximately equivalent to the number of spins in one monolayer. At temperatures between 0.43 and 1 mK the susceptibility has a strong magnetic field dependence. The data are consistent with a simple Landau-Ginzburg model indicating a phase transition at 0.38 mK with a lower than expected magnetization.