Excitons and biexcitons in symmetric electron-hole bilayers
Ryo Maezono, Pablo López Ríos, Richard J. Needs, and Tetsuo Ogawa
Accepted
Symmetric electron-hole bilayer systems have been studied at zero temperature using the diffusion quantum Monte Carlo method. A flexible trial wave function is used that can describe fluid, excitonic and biexcitonic phases. We calculate condensate fractions and pair correlation functions for a large number of densities $r_s$ and layer separations $d$. At small $d$ we find a one-component fluid phase, an excitonic fluid phase, and a biexcitonic fluid phase, and the transitions among them appear to be continuous. At $d=0$, excitons appear to survive down to about $r_s=0.5$~a.u., and biexcitons form at $r_s>2.5$~a.u.