Giant magnetoresistive in soft ferromagnetic multilayers

We show that the in-plane magnetoresistance of sandwiches of uncoupled ferromagnetic (Ni81Fe19,Ni80Co20,Ni) layers separated by ultrathin nonmagnetic metallic (Cu,Ag,Au) layers is strongly increased when the magnetizations of the two ferromagnetic layers are aligned antiparallel. Using NiFe layers, we report a relative change of resistance of 5.0% in 10 Oe at room temperature. The comparison between different ferromagnetic materials (alloys or pure elements) leads us to emphasize the role of bulk rather than interfacial spin-dependent scattering in these structures, in contrast to Fe/Cr multilayers. © 1991 The American Physical Society.