Transport Properties Of Graphene In Electric And Magnetic Field

Graphene is a two-dimensional material in a honeycomb lattice. Graphene has also many novel electronic properties, such as the linear dispersion near zero energy, quantum Hall effect and quantum spin Hall effect. Two-dimensional graphene can be bent into the third dimension, which show some unique quantum transport properties.In planar graphene, the hopping integral of pzorbitals is t ≈ 3.0eV. However, there is a curvature-induced misalignment of the pzorbitals in bent graphene. Thus, the hopping integral should be modified as t0= tcosα(α is the misalignment angle between pzorbitals).The bend under a uniform and perpendicular magnetic field is an ideal system to study effectively nonhomogeneous magnetic fields, since the flux through the nanoribbon changes sign across the fold. This magnetic flux inversion can happen over very short length scales, something more di?cult to achieve in semiconductor heterostructures. Lastly, based on the tight binding model and Green function method, we systematically investigate the effect of electronic field, magnetic field and bent angle to transport properties in bent graphene. Some meaningful results have been obtained.We adopt the tight-binding model to study quantum transport properties of interface and edge states in bent graphene under a magnetic field. In the presence of Zeeman splitting, the electron energy spectrum and quantized conductance are studied. However, in the presence of Zeeman splitting, the spatial distributions of interface states and quantized conductance are different from the case without Zeeman splitting. Moreover, the system can host a quantum spin Hall phase.Based on the tight-binding model, we also use an external electric field to manipulate the interface states, edge states and quantized conductance in folded graphene under a magnetic field. In the presence of Zeeman splitting, we found the number of edge modes is asymmetric on the two edges of folded graphene ribbon. The spatial distributions of interface states and edge states can be manipulated by an external electric field. This provides a feasible method to macroscopically manipulate interface current and edge current.