Ringlike structures in the density–magnetic‐field ρ _xx diagram of two‐subband quantum Hall systems

Abstract

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 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 2D -B diagram, the calculation including exchange and correlation effects (KohnSham) more closely reproduces the ringlike structures in the experiments.

Crossing and anticrossing of spin-split Landau levels in anAlxGa1−xAs∕GaAsYu1, Lockwood2, SpringThorpe3 et al. 2007Phys. Rev. B10050View full textAdd to dashboardCite

“…An "exchange enhanced" g factor ͑g * ͒ is a common means to phenomenologically add complex exchange effects to the single-particle picture of LLs. 7,8,14,24 We take the effective g factor ͉g * ͉ = 9 for the first subband ͑see above͒, and we estimate from the spin splitting of the second subband ͓see the dotted black and solid lines ͑blue online͒ between the dotted black lines in Fig. 3͑a͔͒ ͉g * ͉ for the second subband to be ϳ1.8.…”

Collapse of ρ xx Ringlike Structures in 2DEGs Under Tilted Magnetic Fields

“…The measured electron mobility is µ e = 4.1 × 10 5 cm 2 / Vs. The subband energy splitting ∆ SAS ≈ 14 meV and effective g-factor g * ≈ −1.8 are chosen to adjust the position and size of the ring in the density-magnetic-field diagram 16 .…”

Acoplamento spin-órbita inter-subbanda em heteroestruturas semicondutoras

“…As diferenças são suficientemente pequenas para justificar a aproximação. Entretanto, o efeito dessas pequenas diferenças em cálculos que incluem o termo de troca e correlação não pode ser prevista e talvez as condições de contorno dependentes de spin afete propriedades de sistemas como os estudados nas referências [57,58] onde efeitos coletivos como o ferromagnetismo de efeito Hall são importantes. uma seqüência de sub-bandas contínuas como mostra a Fig.…”