HEAT-CAPACITY OF THIN-FILMS OF HE-4 IN VYCOR NEAR THE CRITICAL COVERAGE

We report on a study of the heat capacity of thin films of He-4 adsorb ed in porous Vycor glass for temperatures between 20 and 700 mK. As in previous work, we find a critical coverage, n(c) approximately 26.6mu moles/m2, above which we find superfludity. For coverages greater than n(c), the heat capacity varies linearly with temperature above the su perfluid transition temperature T(c). We also observe a linear depende nce at high temperatures for coverages below n(c). At lower temperatur es, however, the heat capacity for these coverages decreases with a mu ch stronger temperature dependence. We discuss these data in the conte xt of recent theoretical work on the onset of superfluidity in disorde red systems.