Physical Review B (Condensed Matter) -- March 15,
1997 -- Volume 55, Issue 12,
pp. 7761-7770
Landau-level mixing and spin degeneracy in the quantum Hall effect
V. Kagalovsky, B. Horovitz, and Y. Avishai
Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva,
Israel
(Received 16 October 1996)
We study the dynamics of electrons in a magnetic field using a network
model with two channels
per link with random mixing in a random intrachannel potential; the channels
represent either two
Landau levels or two spin states. We consider channel mixing as a function
of the energy separation of the two extended states and show that its effect
changes from repulsion to attraction as the energy separation increases.
For two Landau levels this leads to level floating at low magnetic fields,
while for Zeeman-split spin states we predict level attraction at high magnetic
fields, accounting for electron spin resonance data. We also study random
mixing of two degenerate channels, while the intrachannel potential is
periodic (nonrandom). We find a single extended state with a localization
exponent 1.1 for real scattering at nodes; the general case also has a single
extended state, though the localized nature of nearby states sets in at
unusually large scales.
©1997 The American
Physical Society
PACS: 73.40.Hm, 71.30.+h