Experiments have confirmed that double monolayer graphene does not generate finite-temperature electron-hole superfluidity, because of very strong screening of the pairing attraction. The linear dispersing energy bands in monolayer graphene block any attempt to reduce the strength of the screening. We propose a hybrid device with two sheets of monolayer graphene in a modulated periodic perpendicular magnetic field. The field preserves the isotropic Dirac cones of the original monolayers but reduces the slope of the cones, making the monolayer Fermi velocity $v_F$ smaller. We demonstrate that with current experimental techniques, the reduction in $v_F$ can weaken the screening sufficiently to allow electron-hole superfluidity at measurable temperatures.

• Received 3 June 2015

DOI:https://doi.org/10.1103/PhysRevB.92.220502

Source: http://link.aps.org/doi/10.1103/PhysRevB.92.220502