Splitting of resistance peaks and anomalous Hall plateaus in asymmetric double-quantum-well structures

The integer quantum Hall effect in asymmetric double-quantum-well structures is investigated. The resistance peaks associated with the Landau levels of the ground subband generate subpeaks when the excited subband is filled with electrons. The split-off peaks shift to higher magnetic fields with increasing electron density. For magnetic fields between the parent and split-off peaks, the Hall resistance shows plateaulike structures. Some of the features can be explained in terms of the crossing of Landau levels originating from the ground and excited subbands at the Fermi energy, although there remain several discrepancies. A self-consistent potential calculation indicates that a fluctuation of the total electron density gives rise to the phenomena.