Exchange and correlation effects on drag in low density electron bilayers: Coulomb and virtual-optical-phonon-mediated electron–electron interaction

We investigate the effect of exchange and correlation (xc) in low-density electron bilayers. Along with the direct Coulomb interaction, the effective electron–electron interaction mediated by the exchange of virtual polar optical (PO) phonons is considered. We find that the introduction of xc corrections results in a significant enhancement of the transresistivity and qualitative changes in its temperature dependence. The virtual PO-phonon contribution behaves similarly to the Coulomb drag and reduces noticeably the total drag thereby resulting in a better agreement with the recent experimental findings.