SPECIFIC-HEAT OF AMORPHOUS HE-3 FILMS AND CONFINED LIQUID-HE-3

We have measured the heat capacities of He-3 films and liquid He-3 in porous Vycor glass at 10 to 600 mK. With increasing the film thickness from 1 to 3 atomic layers, the specific heat evolves gradually from that typical to solid to that of liquid He-3. At about 2 atomic layers, however, its low-temperature part is nearly temperature-independent; we interpret this as a result of gradual freezing of spins in an amorphous solid He-3 film with decreasing the temperature. The contribution of liquid He-3 in the center of the Vycor pores can be described as the specific heat of bulk liquid He-3 at corresponding pressures in the range 0 to 28 bar. The thickness of amorphous solid on the pore walls increases with external pressure roughly linearly. Preplating the walls with He-4 allows to determine the positions of He-3 atoms contributing to the surface specific heat at 10 to 50 mK. In addition, the contribution from the specific heat of He-3 - He-4 mixing at 100 to 600 mK is discussed as a function of pressure and amount of He-4.