Conductance in graphene through double laser barriers and magnetic field

Abstract

Photon-assisted charge transport through a double-barrier laser structure, separated by a region assisted by a magnetic field, is studied. Employing Floquet theory and matrix formalism, the transmission probabilities for the central band and sidebands are calculated. The temporal periodicity of the laser fields creates an infinite number of transmission modes due to the degeneracy of the energy spectrum. The challenge of numerically addressing all modes necessitates the limitation to the first sideband corresponding to energies \(\varepsilon \pm \varpi\). A critical phase difference between the two laser fields is found to cancel the transmission through the sidebands due to quantum interference. Varying the width of the region where the magnetic field is applied allows for the suppression of lateral transmission and control over the transmission mode. The intensity of the laser fields also allows for the suppression of Klein tunneling and blocking transmission processes with zero photon exchange, as well as activating transmission processes with photon exchange. The conductance is also affected by changes in the system parameters. Increasing the intensity of the laser field reduces the conductance due to the confinement of the fermions by the laser fields. In addition, increasing the size of the region where the magnetic field is applied reduces the conductance because the increased distance gives the fermions a greater chance of diffusion and increases their interaction with the magnetic field.