Superfluid density in 3He film

The size effect on the superfluid density rho(s) of He-3 films with thickness of the order of the coherence length is discussed on the basis of the quasi-classical Green's function method. We formulate a linear response theory in He-3 films where the ABM state is stabilized owing to the size effect. This study is motivated by the third sound experiment recently reported by Schechter et al. In this experiment, the superfluid density rho(s) has been obtained for films with thicknesses in the range 92-281 nm. We show that when we assume the scattering from the substrate to be diffusive and that from the free surface of He-3 to be specular, our results reproduce well the temperature dependence of rho(s) measured for films thinner than 174 nm, while the data for thicker films deviate from our ABM results. (C) 2000 Elsevier Science B.V. All rights reserved.