Mesoscopic Electronic Transport in Twisted Bilayer Graphene

TL;DR

This study uses numerical methods to analyze how twist angle, stacking, and axis affect electronic transport in bilayer graphene, revealing tunable conductance properties crucial for nanodevice design.

Contribution

It systematically investigates the influence of twist axis and stacking order on conductance in twisted bilayer graphene using advanced computational techniques.

Findings

Conductance oscillates with twist angle for 'top' axis configurations.

Nearly vanishing conductance near charge neutrality for 'hollow' axis configurations.

Twist axis choice significantly influences interlayer conductance.

Abstract

We numerically investigate the electronic transport properties between two mesoscopic graphene disks with a twist by employing the density functional theory coupled with non-equilibrium Green's function technique. By attaching two graphene leads to upper and lower graphene layers separately, we explore systematically the dependence of electronic transport on the twist angle, Fermi energy, system size, layer stacking order and twist axis. When choose different twist axes for either AA- or AB-stacked bilayer graphene, we find that the dependence of conductance on twist angle displays qualitatively distinction, i.e., the systems with "top" axis exhibit finite conductance oscillating as a function of the twist angle, while the ones with "hollow" axis exhibit nearly vanishing conductance for different twist angles or Fermi energies near the charge neutrality point. These findings suggest that the choice of twist axis can effectively tune the interlayer conductance, making it a crucial factor in designing of nanodevices with the twisted van der Waals multilayers.