Orbital dependent Coulomb drag in electron-hole bilayer graphene heterostructures

TL;DR

This study investigates Coulomb drag in electron-hole bilayer graphene under magnetic fields, revealing orbital-dependent interactions and new drag phenomena influenced by displacement fields in the quantum Hall regime.

Contribution

It demonstrates orbital-dependent Coulomb drag effects and introduces the influence of vertical displacement fields on interlayer interactions in bilayer graphene.

Findings

Coulomb drag observed between N=1 Landau levels under certain conditions

Drag signals vary with increasing displacement field, showing orbital dependence

New interlayer Coulomb interactions emerge between different Landau levels

Abstract

We report Coulomb drag studies in an electron-hole bilayer graphene heterostructure in a magnetic field, where the orbital, spin, and valley degrees of freedom are lifted by the combined effects of exchange interaction, Zeeman energy, and vertical displacement field. Our device enables the application of a large vertical displacement field in both layers. In addition to the well-established strong Coulomb drag between Landau levels with an orbital quantum number N = 0, we observe a Coulomb drag signal between the N = 1 Landau levels under a suitable vertical displacement field. As the displacement field increases further, the Coulomb drag signal between N = 1 Landau levels weakens, and a Coulomb drag signal emerges between the N = 0 and N = 1 Landau levels. These findings suggest the important roles of the orbital index and vertical displacement field in interlayer Coulomb interactions within the quantum Hall regime of coupled bilayer systems.