The spin polarization of current injected from a Permalloy electrode into a mesoscopic Ag wire is measured for samples with very low interface resistance. The observed value of at 79 K is an order of magnitude larger than values previously reported for low resistance interfaces and about 4 times larger than predictions of the common resistance mismatch model. These results demonstrate that high resistance barriers are not necessary for efficient spin injection.

• Received 13 October 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.136601