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Dephasing by extremely dilute magnetic impurities revealed by Aharonov-Bohm oscillations

F. Pierre, Norman O. Birge

cond-mat.mes-hallarXiv:cond-mat/0209562

Abstract

We have probed the magnetic field dependence of the electron phase coherence time τϕ by measuring the Aharonov-Bohm conductance oscillations of mesoscopic Cu rings. Whereas τϕ determined from the low-field magnetoresistance saturates below 1 K, the amplitude of Aharonov-Bohm h/e oscillations increases strongly on a magnetic field scale proportional to the temperature. This provides strong evidence that a likely explanation for the frequently observed saturation of τϕ at low temperature in weakly disordered metallic thin films is the presence of extremely dilute magnetic impurities.

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