Nuclear susceptibility of liquid3He-4He solutions along the demixing line

Pulsed NMR measurements of the nuclear magnetic susceptibility of liquid³He-⁴He solutions at saturated vapor pressure are presented. They extend over the whole temperature range between 50 mK and 825 mK, for both concentrations of the coexisting dilute and³He-rich phases. The results have been compared to those obtained with pure³He, and the temperature dependence of the ratio of molar susceptibilities of coexisting phases is derived. The consequences on the efficiency of fractional distillation as a method to enhance nuclear polarization are discussed.