Coulomb Drag between a Carbon Nanotube and Monolayer Graphene

TL;DR

This study measures Coulomb drag between a single-walled carbon nanotube and monolayer graphene, revealing temperature-dependent behaviors, layer reciprocity breaking at low temperatures, and interaction effects in the hydrodynamic regime.

Contribution

It provides the first experimental observation of Coulomb drag between a 1D nanotube and 2D graphene, highlighting nonlinear effects and hydrodynamic interactions.

Findings

Drag resistance changes sign across the CNP at high temperatures.

Layer reciprocity is broken near the CNP at low temperatures.

Drag exhibits power-law dependence on temperature and carrier density.

Abstract

We have measured Coulomb drag between an individual single-walled carbon nanotube (SWNT) as a one-dimensional (1D) conductor and the two-dimensional (2D) conductor monolayer graphene, separated by a few-atom-thick boron nitride layer. The graphene carrier density is tuned across the charge neutrality point (CNP) by a gate, while the SWNT remains degenerate. At high temperatures, the drag resistance changes sign across the CNP, as expected for momentum transfer from drive to drag layer, and exhibits layer exchange Onsager reciprocity. We find that layer reciprocity is broken near the graphene CNP at low temperatures due to nonlinear drag response associated with temperature dependent drag and thermoelectric effects. The drag resistance shows power-law dependences on temperature and carrier density characteristic of 1D Fermi liquid-2D Dirac fluid drag. The 2D drag signal at high temperatures decays with distance from the 1D source slower than expected for a diffusive current distribution, suggesting additional interaction effects in the graphene in the hydrodynamic transport regime.