Isotropic and energy-selective electron cloaks on graphene

Abstract

We propose and investigate a design for “electron cloaks” comprised of two electrodes, one top gate and one back gate, on either side of a graphene sheet arranged in a concentric disk configuration. Dirac electrons with specific energies can flow through these electron cloaks with negligible scattering, while electrons with different energies experience significant scattering. The scattering widths of the electron cloaks are analyzed using the partial wave formalism applied to the Dirac equation, and the contributions of the first two partial waves to the scattering widths are set to zero simultaneously via a proper combination of the potentials on the two electrodes. We show that this strategy is sufficient for reducing the total scattering widths to below 0.01% of the physical widths of the cloaks. This new design differs from the well-known Klein tunneling phenomenon in that, in our case, the transparency is isotropic and energy selective. These characteristics, in tandem with tunable Fermi levels and/or the gate voltages on the electrodes, enable the electron cloaks to serve as core units in the designs of new sensors, switches, or transistors.