| We numerically study the
resistance fluctuations
of mesoscopic samples, near transitions between Quantum
Hall plateaus recently discovered by E. Peled, et. al.
[Phys. Rev. Lett. {\bf 90}, 246802 (2003); {\bf 90},236802 (2003);
Phys. Rev. B
new reference here (2004)] The
experiment is modeled by realistic first-principles simulations within
non-interacting electron approximation This simulation uses a
six-terminal
geometry and sample sizes similar to those of real devices. The Hall
and
longitudinal resistances extracted from the Landauer formula exhibit
all the
observed experimental features. We
further propose a generalization of the Landauer-Buttiker model, based
on the interplay
between tunneling and chiral currents, to give unified explanations for
the
three regimes with distinct types of fluctuations observed, consistent
with the
scaling theory of integer quantum Hall effect. We identify the central
regime
at intermediate filling factor as the critical region where the
localization length
is comparable to or larger than the sample size. |
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