Coulomb Drag near the metal-insulator transition in two-dimensions

TL;DR

This study investigates Coulomb drag in two-dimensional hole systems near the metal-insulator transition, revealing correlated deviations from expected behavior, the influence of layer spacing on screening, and the impact of drag on resistivity temperature dependence.

Contribution

It provides new insights into the relationship between Coulomb drag, screening, and metallic behavior near the 2D metal-insulator transition.

Findings

Deviations from $T^{2}$ dependence are independent of layer spacing.

Screening weakens as carrier density decreases.

Drag enhances the metallic temperature dependence of resistivity.

Abstract

We studied the drag resistivity between dilute two-dimensional hole systems, near the apparent metal-insulator transition. We find the deviations from the $T^{2}$ 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.