Coherent Graphene Devices: Movable Mirror, Buffer and Memory

We theoretically report that, at a sharp electrostatic step potential in graphene, massless Dirac fermions can obtain a Goos-H\"{a}nchen-like shift under total internal reflection. Based on these results, we study the coherent propagation of the quasiparticles along a sharp graphene \emph{p-n-p} waveguide and derive novel dispersion relations for the guided modes. Consequently, coherent graphene devices (e.g. movable mirror, buffer and memory) induced only by the electric field effect can be proposed.