Uniaxial-stress effects on electronic structures of monolayer and bilayer graphenes

Band structures of deformed monolayer and bilayer graphenes are explored through the tight-binding model. The mechanical effects of the strain on graphene lattices are 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 the energy dispersions, band-edge states, Fermi momenta, 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. The analysis of the stacking sequence shows some important differences between the AA- and AB-bilayer graphenes, such as the relationship between the uniaxial stress and low-energy D(ω), and the zero-gap semimetal-semiconductor transition. The calculated results could be verified by experimental measurements.