The Helmholtz free energy F of the interacting 2-D electron fluid is
calculated nonperturbatively using a mapping of the quantum fluid to a
classical Coulomb fluid [Phys. Rev. Letters, vol. 87, 206404 (2001)]. For
density parameters rs such that rs<~25, the fluid is unpolarized at all
temperatures t=T/EF where EF is the Fermi energy. For lower densities, the
system becomes fully spin polarized for t<~0.35, and partially polarized for
0.35<t< 2, depending on the density. At rs ~25-30, and t ~0.35, an ''ambispin''
phase where F is almost independent of the spin polarization is found. These
results support recent claims, based on quantum Monte Carlo results, for a
stable, fully spin-polarized fluid phase at T = 0 for rs larger than about
25-26.Comment: Latex manuscript (4-5 pages) and two postscript figures; see also
http://nrcphy1.phy.nrc.ca/ims/qp/chandre/chnc