Thermodynamic Properties of Multilayer 3He Films Described by High Temperature Series Expansions of the Multiple Spin Exchange Hamiltonian

We report high precision NMR measurements of the susceptibility of3He films adsorbed on graphite in a the temperature range 4-300 mK using a fine coverage grid between 0.185 and 0.285 atoms/Å2. High temperature series expansions of the multiple spin exchange Hamiltonian fit accurately the susceptibility as well as available heat capacity data, providing a consistent description of the structural and thermodynamic properties of3He films. A long standing paradox for the ferromagnetic regime (heat capacity and susceptibility are described by the Heisenberg model, but with different exchange constants) is quantitatively explained by the MSE model.