Properties of magnetotransport in three-dimensional quantum-dot structures

Magnetotransport through a three-dimensional quantum dot embedded in vertic al quantum wires in the presence of parallel magnetic fields is investigate d theoretically. The conductance spectra and the electron densities are cal culated by the scattering-matrix method. It is found that the characteristi cs of the magnetoconductance depend strongly on the alignments between the quantum wires and the embedded quantum dot. When the central axes of differ ent components are aligned, the conductance spectra are found to be charact erized by antiresonance dips at low magnetic fields and only by plateaus at high magnetic fields, In contrast, when the central axes are misaligned, t he conductance spectra are found to be characterized by a mixture of antire sonance dips and tunnelling peaks in the low-magnetic-held region and only by tunnelling peaks in the high-magnetic-field region. A simple but physica lly motivated model gives an analytical formula which not only compares wel l with but also provides a reasonable explanation for the numerical data. O n the basis of these magnetotransport properties, a method for experimental determination of the alignment of different components in a vertical elect ronic device is proposed.