Equilibrium density of an electron-hole liquid in a strong magnetic field: A possibility of phase separation.

Abstract

The ground state of a model electron-hole liquid (EHL) in a strong magnetic field is investigated. In the regime when only a few Landau subbands are occupied the complex behavior of the equilibrium density leads to a possibility of phase separation. At certain magnetic-field strengths the EHL ground-state energy plotted as a function of the density has two local minima corresponding to two phases with different numbers of Landau subbands occupied. As a result the equilibrium density of EHL will have strong discontinuities as a function of the magnetic field, occurring whenever the relative strength of those minima changes. In a nonequilibrium system, such as a real electron-hole droplet, both phases may be present simultaneously. We discuss several luminescence and infrared absorption experiments, and suggest that they indicate such a phase separation.