Coulomb drag study of dynamic screening in graphene inhomogeneous bilayer system

Abstract

We study coulomb drag phenomena in doped-graphene based electron-electron (e-e) bilayer systems described by non-interacting massless Dirac fermions separated by an insulating layer. The non-zero frequency dependent dynamic screening is taken into account to include the correlations between the two layer using the random phase approximation (RPA) method for long-range and weak interaction limits. Analytically, the frequency-dependent/dynamic response function is presented at finite and non-finite temperatures to consider the dynamic screening. At low temperatures, drag resistivity shows an usual Fermi-liquid behavior. However, a marked improvement has been found in the predictions of the conventional static interaction. Zero-temperature dependent dynamic screening results show $\ge 20\text{\%}$ enhanced drag resistivity (${\rho }_D$) compared to static. Similarly, the dynamic screening at finite temperature result in a significant enhancement and qualitative change than non-finite temperature. The structure concern to non-homogeneous dielectric medium (NHDM) is also studied to consider the screening effects of substrate and uppermost layer into account. The introduction of NHDM structure finds a marked improvement compared to homogeneous dielectric medium (HDM).