Dephasing of conduction electrons by magnetic impurities in Cu/Ni and Cu/Cr samples : Influence of spin-glass transition on the superconducting proximity effect

Theoretische Physik III, Ruhr-Universit¨at Bochum, D-44780 Bochum, Germany andInstitute of Radioengineering and Electronics of the Russian Academy of Sciences, 125009 Moscow, Russia(Dated: February 6, 2008)The dependence of the superconducting proximity effect on the amount of magnetic impurities inthe normal part of Andreev interferometers has been studied experimentally. The dephasing ratesobtained from fitting experimental data to quasiclassical theory of the proximity effect are consistentwith the spin flip scattering from Cr impurities forming a local moment in the Cu host. In contrast,Ni impurities do not form a local moment in Cu and as a result there is no extra dephasing fromNi as long as Cu/Ni alloy remain paramagnetic.I. INTRODUCTION