Formation and Characterization of Correlated Electron States at Room Temperature in Graphene Bilayers

The small dimensions of graphene bilayers suggest that exotic quantum states may be sustainable at room temperatures. In this work, we use quantum many-body computer simulations techniques with experimentally verified inputs to establish the transition temperature of an excitonic condensate in bilayer graphene and explore its transport properties [1]. To make robust predictions of the thermodynamic and transport properties of bilayers. we perform path integral Monte Carlo (PIMC) simulations of electrons and holes in two graphene layers separated by a one-nanometer thick oxide layer, which suppresses tunneling between layers while allowing for strong Coulomb correlations between layers. Top and bottom gates induce electron and hole densities of $5\times10^{12}$~cm$^{-2}$ in the two layers. As we vary the temperature, we see excitonic formation and Bose condensation. We calculate excitonic superfluid density from the winding statistics and estimate T$_c\sim 800$~K, well above room temperature. [1] M. J. Gilbert and J. Shumway, J. Comput.~Electron., {\bf 8}, 51-59 (2009).