Hamburg 2001 – scientific programme
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HL: Halbleiterphysik
HL 15: Quanten-Hall-Effekt
HL 15.1: Talk
Tuesday, March 27, 2001, 10:30–10:45, S16
Macroscopic inhomogeneities at the quantum Hall transition — •P. Cain1, M.E. Raikh2, R.A. Römer1, and M. Schreiber1 — 1Institut für Physik, Technische Universität, D-09107 Chemnitz — 2Department of Physics, University of Utah, Salt Lake City, UT 84112, U.S.A.
We investigate the influence of inhomogeneities on the critical properties of the integer quantum Hall transition by a real-space renormalization group method for the Chalker-Coddington network model. In the uncorrelated case, we find a broad conductance distribution with mean ⟨ G ⟩ = (0.498 ± 0.004) e2/h and correlation length exponent ν0= 2.39 ± 0.01. Macroscopic inhomogeneities are modelled by a scale-invariant power-law-correlated decay of the smooth random potential. Our results suggest that the effective value of ν in the presence of such inhomogeneities is greatly enhanced, ν≥ν0 even for very large system sizes. Thus the effective scaling behavior at the transition is modified. This might support recent experimental studies that observe deviations from the universal scaling behavior [1,2].
[1] D. Sahar et al., Sol. State Comm. 107, 19 (1998)
[2] N. Q. Balaban et al., Phys. Rev. Lett. 81, 4967(1998)