Magnetoconductance oscillations of two parallel quantum wires coupledthrough a potential barrier

Abstract

The magnetotransport properties of dual quantum wires, in which two parallel quasi-one-dimensional quantum wires are coupled through a thin isolating potential barrier, are studied theoretically. It is found that the quantized conductance of such a structure as a function of Fermi energy or magnetic field exhibits square-wave-like oscillations. This character of the conductance is closely related to the energy-dispersion spectrum of electron in the device. Energy-dispersion relations of the structure with various coupling strengths and magnetic-field strengths are calculated and analyzed in detail. It is found that the magnetic field separates the two sets of dispersion curves that belong to different quantum wires in the wave-number space and that the coupling effect between quantum wires introduces energy splits at the cross points of dispersion curves. In the resonant-tunneling regions a pair of edge states around the barrier region with oppositely moving directions are coupled and form a circulating localized state, leading to the quenching of the related propagation modes. The resulting dispersion relations exhibit an oscillation structure superimposed on the bulk Landau levels. It is the oscillatory behavior of the dispersions that leads to the appearance of square-wave modulations in the conductance. The depth and width of the square wave in conductance depend on the strength of the magnetic field applied, the Fermi energy of the electron, and the thickness and height of the isolating potential barrier and widths of the quantum wires. These conductance characteristics may provide potential applications to the fabrication of quantum devices.