Effective mass of electrons and holes in bilayer graphene: Electron-hole asymmetry and electron-electron interaction

Precision measurements of the effective mass m^* in high-quality bilayer graphene using the temperature dependence of the Shubnikov-de Haas oscillations are reported. In the density range 0.7×1012 < n < 4.1×1012 cm^-2, both the hole mass mh* and the electron mass me* increase with increasing density, demonstrating the hyperbolic nature of the bands. The hole mass mh* is approximately 20-30% larger than the electron mass me*. Tight-binding calculations provide a good description of the electron-hole asymmetry and yield an accurate measure of the interlayer hopping parameter v₄=0.063. Both mh* and me* are suppressed compared with single-particle values, suggesting renormalization of the band structure of bilayer graphene induced by electron-electron interaction.