Ringlike structures in the density-magnetic-field ρxx diagram of two-subband quantum Hall systems

Motivated by recent experiments [Zhang et al., Phys. Rev. Lett. 95, 216801 (2005) and Ellenberger et al., cond-mat/0602271] reporting novel ringlike structures in the density–magnetic-field (n2D–B) diagrams of the longitudinal resistivity ρxx of quantum wells with two subbands, we investigate theoretically here the magneto-transport properties of these quantum-Hall systems. We determine ρxx via both the Hartree and the Kohn-Sham self-consistent schemes plus the Kubo formula. While the Hartree calculation yields diamondshaped structures in the n2D–B diagram, the calculation including exchange and correlation effects (Kohn-Sham) more closely reproduces the ringlike structures in the experiments. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)