Torsion pendulum studies of thin 3He slabs

A high precision torsional oscillator has been developed for the detection of two dimensional superfluidity in 3He films of thickness comparable to the superfluid coherence length, 70 nm at T=0. The mass loading from such a film can be detected with a 0.1% resolution. Measurements on normal films show an unexpected de-coupling from the surface with decreasing temperature, below 60 mK. The frequency shift and dissipation data can be interpreted using a phenomenological interfacial friction model