We report measurements of the magnetoresistance (MR) of narrow Au wires coupled to a superconducting Al contact on one end, and a normal Au contact on the other. The MR at low magnetic field B is quadratic in B, with a characteristic field scale Bc determined by phase coherent paths which encompass not only the wire, but also the two contacts. Bc is essentially temperature independent at low temperatures, indicating that the area of the phase coherent paths is not determined by the superconducting coherence length LT in the normal metal, which is strongly temperature dependent at low temperatures. We identify the relevant length scale as a combination of the electron phase coherence length Lϕ in the normal metal and the coherence length ξS in the superconductor.
@article{arxiv.cond-mat/0103574,
title = {Magnetoresistance of proximity coupled Au wires},
author = {D. A. Dikin and M. J. Black and V. Chandrasekhar},
journal= {arXiv preprint arXiv:cond-mat/0103574},
year = {2009}
}