We report heat capacity and magnetisation measurements of
3He adsorbed on the surface of graphite plated with three atomic layers of
4He. For
3He coverages
n 3>4 nm
?2 the heat capacity corresponds to a 2D Fermi fluid. The inferred hydrodynamic mass of the
3He quasiparticles is 1.38±0.05 m
3. The
3He effective mass ratio increases with coverage to 2.4 at
n 3=4 nm
?2, due to Fermi liquid interactions. The heat capacity isotherm exhibits a steplike increase centred on
n 3=4.5 nm
?2, similar to that previously observed on four layers of
4He. This is associated with the population of the first excited Andreev surface bound state. However, in the present case, as
n 3 is increased through the step a pronounced anomalous feature develops in the temperature dependence of the heat capacity, around 10 mK. Below 5 mK the heat capacity is approximately linear in temperature. With
n 3=7 nm
?2, we find that this behaviour is very sensitive to small changes in the
4He third layer coverage, around the completed third layer. Measurements of the
3He magnetisation,, by continuous wave NMR methods, find a significant increase with decreasing temperature below around 20 mK. Together the data suggest that a phase transition takes place in the film at low mK temperatures.
相似文献