Tunable electronic transport and unidirectional quantum wires in graphene subjected to electric and magnetic fields

Magnetic barriers in graphene are not easily tunable. Here we show that the application of both electric and magnetic fields provides tunable and far more controllable electronic states in graphene. In particular, a one-dimensional channel (quantum wire) can be created, which supports localized electron-hole states with parameters tunable by the electric field. Such quantum wire offers peculiar conducting properties, such as unidirectional conductivity and robustness to disorder. Two separate quantum wires comprise a waveguide with two types of eigenmodes: one type is similar to traditional waveguides, the other type is formed by coupled surface waves propagating along the boundaries of the waveguide.