Suppression of impurity and interface-roughness back-scattering in double quantum wires: theory beyond the Born approximation

The effect of higher-order corrections to the Born approximation is studied for the previously obtained giant conductance enhancement in tunnel-couple d double quantum wires in a magnetic field by including both impurity and i nterface-roughness scattering. The enhancement is caused by an abrupt suppr ession of back-scattering of electrons which occurs when the chemical poten tial is in the anticrossing gap of the ground tunnel-split doubler. The cal culated conductance enhancement is large, and the relative higher-order cor rection to the enhancement is found to be significant for long-range scatte ring potentials. However, this relative higher-order correction will be red uced as the range of scattering potentials becomes small. The correction de pends on various effects, such as the magnetic field, electron and impurity densities, impurity positions, symmetric and asymmetric doping profiles, c entre barrier thickness, and degree of interface roughness.