STRUCTURE AND MAGNETISM OF 2ND-LAYER SOLID HE-3 FILMS IN THE INTERMEDIATE REGIME

We report a detailed investigation of the second solid layer of He-3 a dsorbed on graphite in the intermediate coverage range where the magne tic susceptibility displays an evolution from antiferromagnetism to fe rromagnetism. Different interpretations have been proposed for the unu sual magnetic properties of this system in the narrow coverage region around rho = SO atoms/nm(2) where the Curie temperature vanishes, Our results are consistent with the hypothesis that a first order structur al phase transition occurs in this coverage range. We suggest that hea t capacity data do not rule out this interpretation.