QUANTUM TRANSPORT IN AN H-SHAPED WIRE AND A RING STRUCTURE

We have numerically studied the transport properties of an H shaped qu antum wire structure acid a circular quantum ring structure by using t he mode matching technique. We have observed that for the H structure, anomalous Hall resistance plateaus exist in relatively low magnetic f ields as precursors of integer Hall plateaus. We have found that the r esonance patterns of the nonlocal resistance are mainly caused by inte r-mode transitions between two highest modes in the system, yielding l arge oscillations with a mixing frequency in the resistance curve with respect to the width of the bridge-like part of the H structure. For the ring structure, we have found that two oppositely circulating inte rnal waves contribute to the Aharonov-Bohm oscillations, producing bea ting in the transmission amplitudes.