Effects of intra-layer correlations on electron-hole double-layer superfluidity

We investigate the correlations acting within the layers in a superfluid system of electron-hole spatially separated layers. In this system of quasi-dipoles, the dominant correlations are Hartree–Fock. We find in the BEC regime of the superfluid where screening is negligible, that the effect of the correlations on superfluid properties is also negligible. However, in the BCS-BEC crossover regime, where the screening plays a crucial role, we find that the superfluid gap is significantly weakened because the correlations significantly boost the number of low-energy particle-hole excitations participating in the screening process. Finally, the intralayer correlations are found in this system to suppress a predicted phenomenon in which the average pair size passes through a minimum as the crossover regime is traversed. In the presence of intralayer correlations, the minimum is either extremely weak or completely absent.