Tunable Band Structure Effects on Ballistic Transport in Graphene Nanoribbons

TL;DR

This paper explores how perpendicular electric and magnetic fields can dramatically alter the band structure and ballistic transport in graphene nanoribbons, revealing tunable electronic properties and conductance oscillations.

Contribution

It demonstrates the combined effects of electric and magnetic fields on GNR band structure, showing how they induce chiral Dirac points, Landau levels, and conductance oscillations, which were not previously characterized together.

Findings

Electric field induces multiple chiral Dirac points.

Magnetic field creates Landau levels and surface states.

Combined fields cause conductance oscillations.

Abstract

Graphene nanoribbons (GNR) in mutually perpendicular electric and magnetic fields are shown to exhibit dramatic changes in their band structure and electron transport properties. A strong electric field across the ribbon induces multiple chiral Dirac points, closing the semiconducting gap in armchair GNR's. A perpendicular magnetic field induces partially formed Landau levels as well as dispersive surface-bound states. Each of the applied fields on its own preserves the even symmetry $E_{k} = E_{-k}$ of the subband dispersion. When applied together, they reverse the dispersion parity to be odd and gives $E_{e,k} = -E_{h,-k}$ and mix the electron and hole subbands within the energy range corresponding to the change in potential across the ribbon. This leads to oscillations of the ballistic conductance within this energy range.