Lattice Effects in the Complex Subband Dispersion of 2DEG Semiconductor Waveguide Structures Subjected toa Perpendicular Magnetic Field

In modeling waveguide magneto-transport experiments (in a quasi-two dimensional electrongas), it is important to have knowledge of the electronic states in a magnetic field perpendicularto the plane of the waveguide confinement potential. We present numerical results, withina lattice model, for the full complex subband dispersion of a rectangular waveguide. The formof our numerical real-subband solutions agrees well with analytical real solutions. However,some of our numerical evanescent solutions have a different topology from the analytic evanescentsolutions near the bandedges. We argue that our evanescent solutions, although consistentwith the symmetry of the lattice model and mode conservation in the restricted Hilbertspace of the discretized Hamiltonian, yield different results that are forbidden in the continuumsolutions. This is a concern for numerical solutions