Giant magnetoresistive in soft ferromagnetic multilayers

We show that the in-plane magnetoresistance of sandwiches of uncoupled ferromagnetic (${\mathrm{Ni}}_{81}$${\mathrm{Fe}}_{19}$,${\mathrm{Ni}}_{80}$${\mathrm{Co}}_{20}$,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.