DECOHERENCE INDUCED BY MAGNETIC IMPURITIES IN A QUANTUM HALL SYSTEM
Kagalovsky V., Chudnovskiy A.L.

Received: November 15, 2012

DOI: 10.7868/S0044451013040149

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Scattering by magnetic impurities is known to destroy coherence of electron motion in metals and semiconductors. We investigate the decoherence introduced in a single act of electron scattering by a magnetic impurity in a quantum Hall system. For this, we introduce a fictitious nonunitary scattering matrix \cS for electrons that reproduces the exactly calculated scattering probabilities. The strength of decoherence is identified by the deviation of eigenvalues of the product \cS\cS^\dagger from unity. Using the fictitious scattering matrix, we estimate the width of the metallic region at the quantum Hall effect inter-plateau transition and its dependence on the exchange coupling strength and the degree of polarization of magnetic impurities.