LOW-TEMPERATURE HEAT-CAPACITIES OF LIQUID-HE-3 THIN-FILMS

We have measured the heat capacity of He-3 thin films adsorbed on grap hite at an areal density of 15.0 nm(-2) down to as low as 100 mu K. Th e second-layer He-3 behaves as a degenerate 2D Fermi fluid in the whol e temperature range we studied. We observed no anomalous behavior in t he heat capacity near 3 mK in contradiction to the recent report by ot her workers. This indicates that possible superfluid transitions would be below 100 mu K. Instead, a small and temperature-independent contr ibution to the heat capacity teas observed, which we attribute to nucl ear-spin degrees of freedom in glassy solid He-3 trapped in substrate heterogeneities.