Thermodynamic properties of thin films of superfluid ³He-A

The pairing correlations in superfluid ₃He are strongly modified by quasiparticle scattering off a surface or an interface. We present theoretical results and predictions for the order parameter, the quasiparticle excitation spectrum, and the free energy for thin films of superfluid ₃He. Both specular and diffuse scatterings by a substrate are considered, while the free surface is assumed to be a perfectly reflecting specular boundary. The results are based on self-consistent calculations of the order parameter and quasiparticle excitation spectrum at zero pressure. We obtain results for the phase diagram, free energy, entropy, and specific heat of thin films of superfluid₃He.