Stark Ladders in a Two-Dimensional Tight-Binding Lattice

概要

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Electronic states of a two-dimensional tight-binding model in a uniform electric field are studied. Numerical solutions for eigenenergies and eigenfunctions are presented as functions of the angle between the electric field and the symmetry axis of the lattice. When the direction of the electric field is [M, N], where M and N are mutually prime each other and MN≠0, the eigenenergies are shown to be quantized with an interval equal to the potential drop between the nearest neighbor net lines. Though the level separation varies discontinuously with the change of the direction, the density of states is shown to be independent of the direction of the electric field, except for the direction [1 0] where the motions parallel and perpendicular to the electric field directions are separable. Unexpected gaps open near the band edges for appropriate electric fields, the magnitudes and the positions of which are smooth functions of the angle for a fixed electric field. The effects of the system edges are also discussed.
社団法人日本物理学会の論文
1993-08-15