SPECIFIC-HEAT AND CURIE-TEMPERATURE EVALUATION ON TRIANGULAR LATTICE - EXCHANGE FREQUENCIES FOR HE-3 ADSORBED ON GRAFOIL, EVALUATED BY PATH INTEGRAL TECHNIQUES

We compute, using path integrals, the cyclic-exchange frequencies of a monolayer of 3He adsorbed on graphite in the incommensurate solid phase. Interactions between helium atoms are treated with the Aziz potential; between an helium atom and the plan of graphite we use an interaction potential which depends only on the distance above the surface. The specific heat (C(v)) and the magnetic susceptibility (chi) are evaluated from the calculated multiple-exchange hamiltonian. The C(v) value converges with the 2-, 3- and 4-body exchange cycles while larger cycles are needed for the convergence of the chi value. For the density 0.0785 atom/angstrom2, we find that the variations of C(v) is antiferromagnetic, whereas the variations of chi is ferromagnetic.