Heat-Capacity Studies of ³He in ³He-⁴He Mixture Films and the Coverage Dependence of the Two-Dimensional ³He Landau Fermi-Liquid Parameters

The heat capacity of ³He in ³He-⁴He mixture films on a nuclepore substrate is reported over the temperature range 90<T<124mK, for ³He coverages between 0.05 and 1.4 bulk-density atomic layers, and a ⁴He film thickness of 4.33 bulk-density atomic layers. A step structure appears in the specific heat as a function of ³He coverage. Combining NMR and specific heat data for ³He atoms on the same substrate and for the same ⁴He coverage allows the two-dimensional Landau Fermi-liquid parameters F₀^A and F₁^S to be extracted as a function of ³He coverage. We conclude that in the submonalayer ³He coverage regime p-state pairing is favored.