Frictional Effects in Thin 3He Films

Abstract

The recent high-precision torsional oscillator experiments of Casey et al. involving thin films of normal liquid 3He showed that the film decouples from the substrate with a time constant $$\tau_{\mathrm{osc}}$$ which is proportional to T −1 where T is the absolute temperature. We interpret this experiment by adapting a theory due to Meyerovich which was developed for dilute 3He-4He mixtures flowing between two relatively smooth plates. The analysis of the experiment confirms the central idea that $$\tau_{\mathrm{osc}}$$ varies as T −1. The variation of $$\tau _{\mathrm{osc}}$$ with film thickness, d, is affected by the change in the shape of the free surface of the film, due to van der Waals forces, as the film becomes thinner.