Coulomb drag near the metal-insulator transition in two dimensions

We studied the drag resistivity between dilute two-dimensional hole systems, near the apparent metal-insulator transition. We find the deviations from the T² dependence of the drag to be independent of layer spacing and correlated with the metalliclike behavior in the single-layer resistivity, suggesting they both arise from the same origin. In addition, layer-spacing dependence measurements suggest that while the screening properties of the system remain relatively independent of temperature, they weaken significantly as the carrier density is reduced. Finally, we demonstrate that the drag itself significantly enhances the metallic T dependence in the single-layer resistivity.