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 x 10(12) < n < 4.1 x 10(12) cm(-2), both the hole mass m(h)* and the electron mass m(e)* increase with increasing density, demonstrating the hyperbolic nature of the bands. The hole mass m(h)* is approximately 20-30% larger than the electron mass m(e)*. Tight-binding calculations provide a good description of the electron-hole asymmetry and yield an accurate measure of the interlayer hopping parameter upsilon(4) = 0.063. Both m(h)* and m(e)* are suppressed compared with single-particle values, suggesting renormalization of the band structure of bilayer graphene induced by electron-electron interaction.