EFFECT OF INTERMIXING ON THE MAGNETIC-PROPERTIES OF CO50FE50 NI80FE20MULTILAYERS/

The effect of interface mixing on the magnetic properties of multilaye r thin films consisting of N Co50Fe50/Ni80Fe20 bilayers was investigat ed for N=1-25. A fixed 50 Angstrom Ni80Fe20 thickness was used in all the multilayers, but the Co50Fe50 layer thickness was varied as 1260 A ngstrom/N. With increasing N, the saturation magnetorestriction (lambd a(s)) of the multilayer films increased from 40 to 58 ppm, but both th e anisotropy field (H-k) and the coercivity (H-c) decreased, from 86 a nd 30 Oe, to 20 and 2.5 Oe, respectively. lambda(s) varied linearly wi th the 1/modulation thickness (D), confirming that the increase was du e to interface mixing in the bilayers. From x-ray data, and the variat ions of the saturation magnetization (4 pi M-s) and resistivity (rho) of the multilayers, it was determined that the interfacial layer resul ted from the diffusion of Fe from the NiFe layers into the CoFe layers . The sensitivity (d lambda/dH), and the permeability of the multilaye rs also increased with N. The utility of this combination. of properti es for magnetostrictive sensor applications has been demonstrated in a related work. (C) 1997 American Institute of Physics.