Layer selective determination of magnetization vector configurations in an epitaxial double spin valve structure: Si(001)/Cu/Co/Cu/FeNi/Cu/Co/Cu

The magnetization vector configurations in an epitaxial Si(001)/Cu/Co/Cu/Fe20Ni80/Cu/Co/Cu double spin valve structure have been investigated at room temperature using polarized neutron reflectivity measurements. The layer-averaged magnetic moment per FeNi atom was found to be 0.99 +/- 0.06 mu(B) at saturation, while the top (bottom) Co layer moment was 1.69 +/- 0.09 mu(B) (1.67 +/- 0.08 mu(B)), which are identical to the bulk values within experimental error. Furthermore, the Co magnetization vectors are found to lie in-plane but canted with respect to the applied field direction for an applied field strength smaller than the coercive fields (similar to 80 and 130 Oe) of the Co layers. This result indicates that a complete antiparallel alignment of the layer magnetizations is not reached causing a corresponding reduction in the giant magnetoresistance (GMR). These observations emphasize the importance of the detailed spin configuration in determining the GMR amplitude at low fields. (C) 2000 American Institute of Physics. [S0003-6951(00)03630-5].