Evidence for a Mott-Hubbard transition in a two-dimensional He-3 fluid monolayer

The heat capacity and magnetization of a fluid He-3 monolayer adsorbed on graphite plated with a bilayer of HD have been measured in the temperature range 1-60 mK. Approaching the density at which the monolayer solidifies into a root7xroot7 commensurate solid, we observe an apparent divergence of the effective mass and magnetization corresponding to a T = 0 Mott-Hubbard transition between a 2D Fermi liquid and a magnetically disordered solid. The observations are consistent with the Brinkman-Rice-Anderson-Vollhardt scenario for a metal-insulator transition. We observe a leading order T-2 correction to the linear term in heat capacity