Low-energy electronic properties of the AB-stacked few-layer graphites

Infrared and Raman spectra of AA-stacking bilayer graphene

The infrared (IR) absorption and resonant Raman spectra of the undoped AA-stacking bilayer graphene have been calculated using density-functional theory in the local density approximation. It is found that the undoped AA-stacking bilayer graphene exhibits a different characteristic jump and peak structure in its IR spectra, and a different G-band peak structure in its resonant Raman spectra, compared with those of the AB-stacking one, which are caused by the different interlayer coupling effects, due to different stacking types in both of them. Based upon the different IR and Raman spectra, a powerful experimental method can be proposed to identify accurately the stacking type and the layer number in future experiments.

Modulation effects on Landau levels in a monolayer graphene

Magnetoelectronic properties of a single-layer graphene are studied by the Peierls tight-binding model. A new numerical technique is developed to obtain a band-like Hamiltonian matrix. A spatially modulated magnetic field B' could drastically alter the Landau levels due to a uniform magnetic field B. The modulation effects include enhancement in dimensionality, change of energy dispersions, destruction of state degeneracy and creation of band-edge states. The dispersionless Landau levels, those at the Fermi levels excepted, become the 1D parabolic bands. The density of states thus exhibits many pairs of asymmetric prominent peaks. The height, frequency and number of pronounced peaks strongly depend on the modulation strength. These characteristics are hardly affected by the period and direction when B' is much weaker than B. The predicted results could be verified by experimental measurements on magneto-optical absorption spectra.