He3-He4mixtures in two dimensions

Abstract

In this paper we discuss the thermodynamic properties of a physisorbed mixture of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. We present microscopic calculations of the zero-temperature liquid-gas and phase-separation aspects and extend these results to finite temperature, in an approximate way, using a simple model. The results are then compared to the recent experimental data of Hickernell, McLean, and Vilches on ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixtures on graphite. We conclude that the low-density phases of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ on graphite are not well understood and in particular the identification of the major structures in the experimental data as the liquid-gas transition is not straightforward.