Molecular dynamics studies of electron-hole bilayers

Abstract
We investigated the properties of strongly coupled classical electron-hole bilayers, using a molecular dynamics simulation code based on the PPPM (particle-particle particle-mesh) algorithm and applying the transformation of the two layers into a single layer with modified interaction potentials. The calculations were carried out for layer separations d comparable to the Wigner-Seitz radius a. The analysis of the (intra- and interlayer) pair correlation functions g₁₁(r) and g₁₂(r) showed that at layer separations d/a ≥ 3 the layers are independent of each other. With decreasing d/a a strongly increasing peak of g₁₂ develops at r/a = 0, indicating the formation of electron-hole pairs ("classical excitons"). The intralayer correlation function g₁₁ is essentially independent of the layer separation for d/a ≥ 1, the interaction of particles between the two layers does not influence the long range order (observed at high d/a < 1 values) in the layers. At d/a < 1 the long range order is destroyed due to the fact that the interaction is due to the dipole field of the electron-hole pairs.