Magnetic-field-induced resonant tunneling through a microjunction in a quantum wire

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Abstract
We study a microjunction in a two-dimensional electron gas under the action of a uniform magnetic field, orthogonal to the gas plane. The microjunction is modeled as an infinite rectilinear waveguide with parabolic walls interrupted by a barrier. Low magnetic fields suppress the backscattering and improve the conductance quantization with sharper transmission steps. At higher field values an unexpected feature emerges: the resonant tunneling through the barrier. Just near the threshold, at energies for which the traversal of the barrier is classically forbidden, well-defined transmission peaks appear which correspond to quasibound states trapped inside the barrier.