Nuclear magnetism of normal 3He and 3He-4He mixtures in aerogel

We report NMR experiments at 8 T on He-3 and He-3-He-4 mixtures filling the pores of 95% porous aerogel, for temperatures T greater than or equal to 6 mK. Magnetization measurements of pure He-3 reveal a localized layer approximately one monolayer thick. The longitudinal relaxation includes a component logarithmic in time, which is apparently associated with a fraction of the localized He-3 atoms. When the localized He-3 is displaced by adding He-4 the logarithmic relaxation disappears and T-1 for the dominant exponential relaxation increases. Measurements of the spin diffusion coefficient with the aerogel filled with dilute solution in equilibrium with bulk phase-separated mixture provide an unambiguous determination of the spin mean free path, l(s) = 58 nm.