Reduction of the normal-superfluid transition temperature in gated bilayer graphene

Abstract

We show that the normal-superfluid transition in bilayer graphene (BLG) predicted to occur at high temperature is strongly affected not only by the dielectric constants of the insulators, but also by the proximity of ideal metal gates. Even assuming optimistically an unscreened interlayer Coulomb interaction, we find that for a gate-insulator thickness smaller than 2-to-5 nm of equivalent SiO2 thickness, the transition temperature is depressed to the 1 K-1 mK range. Thus, thicker and low-κ gate insulators are required to design transistors exploiting the properties of the superfluid state.