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

TL;DR

This study investigates how magnetic impurities like Cr and Ni affect electron coherence in Cu-based samples, revealing that Cr causes dephasing due to local moments, while Ni does not when paramagnetic.

Contribution

It provides experimental evidence on how different magnetic impurities influence electron dephasing and the superconducting proximity effect in Cu alloys.

Findings

Cr impurities cause dephasing via local moments.

Ni impurities do not induce dephasing in paramagnetic Cu/Ni alloys.

Dephasing rates align with spin flip scattering models.

Abstract

The dependence of the superconducting proximity effect on the amount of magnetic impurities in the normal part of Andreev interferometers has been studied experimentally. The dephasing rates obtained from fitting experimental data to quasiclassical theory of the proximity effect are consistent with 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 from Ni as long as Cu/Ni alloy remain paramagnetic.