Equilibrium phase diagram and kinetics of isotopical phase separation of 3% 3He in HCP 4He mixture

The isotopical phase separation in a weak solid mixture of 3He in 4He is investigated by 250 kHz pulsed NMR under a pressure of 3.7 MPa in the temperature range 100 - 240 mK. The equilibrium concentrations of 3He in HCP phase are found to be in a good agreement with classical regular solution theory for phases with different crystal structures. The time constant of decay at steplike cooldown along the separation line are shown to monotonously decrease. The linear dependence of the time on the concentration may point towards an important role of quantum diffusion