Semi-Dirac point and its transport properties in two-dimensional deformed hexagonal lattice

摘要

We investigate the effect of uniaxial tensile stress on the electronic structure and transport properties of hexagonal lattice via a tight-binding approach. We find two Dirac points merging into a single point to generate a semi-Dirac cone as the tensile stress increases. The semi-Dirac cone is anisotropic with linear and parabolic dispersions at distinct directions. For a larger tensile stress, a band gap can be opened which indicates a phase transition from metallic phase to insulator phase. In the presence of magnetic field, the degeneracies of all Landau levels are lifted only partially yielding an unconventional Hall conductance with a step size of 2e(2)/h at each non-equidistant Landau level.