Ringlike structures in the density–magnetic‐field ρ xx 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 ( n 2 D – B ) diagrams of the longitudinal resistivity ρ xx of quantum wells with two subbands, we investigate theoretically here the magneto‐transport properties of these quantum‐Hall systems. We determine ρ xx via both the Hartree and the Kohn‐Sham self‐consistent schemes plus the Kubo formula. While the Hartree calculation yields diamondshaped structures in the n 2 D – 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)