Band-unfolding approach to Moir\`e-induced band-gap opening and Fermi-level-velocity reduction in twisted bilayer graphene

摘要

We report on the energy spectrum of electrons in twisted bilayer graphene(tBLG) obtained by the band-unfolding method in the tight-binding model. Wefind the band-gap opening at particular points in the reciprocal space, thatelucidates the drastic reduction of the Fermi-level velocity with the tinytwisted angles in tBLGs. We find that Moir\`e pattern caused by the twist ofthe two graphene layers generates interactions among Dirac cones, otherwiseabsent, and the resultant cone-cone interactions peculiar to each point in thereciprocal space causes the energy gap and thus reduced the Fermi-levelvelocity.