Quasi-2D Liquid He-3

Abstract

Quantum Monte Carlo simulations at zero temperature of an ensemble of 3 He atoms adsorbed on Mg and Alkali substrates yield strong evidence of a thermodynamically stable liquid 3 He monolayer on all Alkali substrates, with the possible exception of Li. The effective 2D density is θ ≈ 0.02 Å−2 on Na, making it the lowest density liquid in Nature. Its existence is underlain by zero-point atomic motion perpendicular to the substrate, whose effect is softening the short-range repulsion of the helium interatomic potential. The monolayer films should turn superfluid at a temperature Tc ∼ 1 mK. No liquid film is predicted to form on Mg, or on stronger substrates such as graphite.