Resistance and spin-direction memory loss at Nb/Cu interfaces

A new method is described for measuring the loss of spin-direction memory ( spin relaxation) in nonmagnetic materials and at nonmagnetic interfaces. Th e method involves inserting the material of interest into an exchange-biase d spin valve and monitoring the associated reduction in the spin valve's ma gnetoresistance measured with the current perpendicular to the planes. This technique is tested by investigating spin relaxation near Nb/Cu interfaces . A surprisingly large loss per interface is found, between 15% and 25% wit h larger values being associated with thicker Nb layers. (C) 1999 American Institute of Physics. [S0021-8979(99)19208-9].