The electronic and transport properties of monolayer and AB-stacked bilayer
zigzag graphene nanoribbons subject to the influences of a magnetic field are
investigated theoretically. We demonstrate that the magnetic confinement and the
size effect affect the electronic properties competitively. In the limit of a strong
magnetic field, the magnetic length is much smaller than the ribbon width, and
the bulk electrons are confined solely by the magnetic potential. Their properties
are independent of the width, and the Landau levels appear. On the other hand,
the size effect dominates in the case of narrow ribbons. In addition, the dispersion
relations rely sensitively on the interlayer interactions. Such interactions will
modify the subband curvature, create additional band-edge states, change the
subband spacing or the energy gap, and separate the partial flat bands. The band
structures are symmetric or asymmetric about the Fermi energy for monolayer or
bilayer nanoribbons, respectively. The chemical-potential-dependent electrical
and thermal conductance exhibits a stepwise increase behaviour. The competition
between the magnetic confinement and the size effect will also be reflected in the
transport properties. The features of the conductance are found to be strongly
dependent on the field strength, number of layers, interlayer interactions, and
temperature.
Relation:
Philosophical Magazine Vol. 89, No. 8, 11 March 2009, 697–709