Magnetic field control of current through model graphene nanosheets

Abstract

We study magnetic field control of current through model graphene nanosheet junctions within the framework of the tight-binding approximation. Geometrical asymmetry in the coupling of graphene nanosheets to the contact leads emerges as one of the most important determining factors for the magnetic field control of current. The asymmetric connection split the otherwise degenerate energy levels of the structures leading to energy-resolved transmission peaks which the applied field modulates for a transmission maximum by narrowing the energy gap between the split energy levels. Also, the contact coupling strength plays a decisive role in controlling current in small structures, while its role is significantly less in large structures that have more closely-spaced energy levels. Model calculations on a graphene nanosheet junction with inter-site Coulomb interaction is found to sustain sensitivity to the applied magnetic field. Although several factors bear direct effect on the electron transport through molecular junctions, suitably constructed graphene nanosheet junctions would greatly enhance the prospects of current control under applied magnetic fields.