Strong correlations in two-dimensional quantum fluids of 4He and 3He adsorbed on hectorite

Quantum fluids, of 4He and3He adsorbed on mesopores of Hectorite were studied by measuring the heat capacity down to 50mK. Phonon and roton-like heat capacities of the two-dimensional (2D) superfluid were observed as a function of the coverage. Comparisons with model calculations suggest a strong correlation between the adatoms of which an effective hard core diameter is 4-6 angstrom. At the coverage and temperatures corresponding to the superfluid the3He adatoms show a large nuclear heat capacity probably due to a Fermi degeneracy. The temperature-linear region the3He heat capacity is likely to be much lower than that expected for an ideal Fermi gas. Assuming a 2D Fermi liquid, the effective mass at the coverage of about 2 layers is estimated to be 2.5 times that of the3He atom