Electric Field Dependence of Excitation Spectra in AB-Stacked Bilayer Graphene

The single- and many-particle Coulomb excitation spectra in Bernal bilayer graphene can be modulated by a uniform perpendicular electric field. The field-induced oscillatory parabolic bands possess saddle points and local extrema, which, respectively, lead to logarithmically divergent peaks and discontinuous steps in the bare response functions. Such special structures are associated with the plasmon peaks in the screened loss spectra. Their main characteristics, such as their existence, frequency, and strength, vary strongly with the field strength and transferred momentum. The predicted results could be further examined by inelastic light scattering spectroscopy and electron-energy-loss spectroscopy.