arXiv:1208.0842 · Physical Review Letters
Observation of Self-Binding in Monolayer He3
D. Sato, K. Naruse, Tomohiro Matsui, Hiroshi Fukuyama
Abstract
We report clear experimental signatures of the theoretically unexpected gas-liquid transition in the first three monolayer systems of $^{3}\mathrm{He}$ adsorbed on graphite. The transition is inferred from the linear density dependence of the gamma coefficient of the heat capacity measured in the degenerate region ($2\ensuremath{\le}T\ensuremath{\le}80\text{ }\text{ }\mathrm{mK}$) below a critical liquid density (${\ensuremath{\rho}}_{c0}$). Surprisingly, the measured ${\ensuremath{\rho}}_{c0}$ values ($0.6--0.9\text{ }\text{ }{\mathrm{nm}}^{\ensuremath{-}2}$) are nearly the same for all these layers in spite of their quite different environments. We conclude that the ground state of $^{3}\mathrm{He}$ in strictly two dimensions is not a dilute quantum gas but a self-bound quantum liquid with the lowest density ever found.