Phases of He-3-He-4 mixtures in two dimensions - art. no. 054504

We calculate the phase diagram of He-3-He-4 mixtures in two dimensions as a function of density and He-3 concentration. A number of features distingui sh this system significantly from its three-dimensional counterpart. Specif ically, we find that the He-3 phase consists, at low He-3 concentrations an d positive pressures, of loosely bound dimers. The dimerized liquid phase s eparates at a He-3 concentration of 2-3 % because the chemical potential of the He-3 component in the mixture exceeds the chemical potential in the pu re phase. Atomic He-3-He-4 mixtures can be found only in a metastable state in a concentration regime above 3 %, where the mixture is stable against i nfinitesimal concentration fluctuations. The softening of concentration-flu ctuation modes with decreasing He-3 concentration is accompanied by a diver gence of the He-3 hydrodynamic effective mass, and the magnetic susceptibil ity vanishes. We verify, wherever possible, that our results are consistent with simulation data and exact estimates.