Deformation effects on electronic structures of bilayer graphenes

The deformation effects on the electronic properties of AA- and AB-stacked bilayer graphenes are explored through the tight-binding model. The mechanical deformation of graphene lattices is based on the elasticity theory. Electronic properties are dependent on the existence of uniaxial stress, interlayer interactions, and the stacking sequence. Uniaxial stress drastically changes energy dispersions, band-edge states, state degeneracies, and density of states (D(ω)). The interlayer interactions induce two pairs of band structures and double the number of the special structures in D(ω). Each prominent peak at the middle energy splits into two separate peaks in the presence of uniaxial stress. Analysis of the stacking sequence shows some important differences between AA- and AB-bilayer graphenes, such as the relationship between uniaxial stress and the low-energy D(ω), and zero-gap semimetal-semiconductor transition. The calculated results could be verified by experimental measurements.