Structural and magnetic properties of Fe/Ni and Fe/Co multilayers

Fe/Ni and Fe/Co multilayers (ML) have been deposited by dc triode sputtering, with a layer thickness (t) in the range 1–10 nm. For t≳4 nm both metals are in crystalline form (bcc Fe, fcc Ni, hcp Co). For t<2 nm one has a single-phase structure (fcc in Fe/Ni ML, bcc in Fe/Co ML) which can be explained by assuming the presence of a 1-nm-thick mixed layer at the interfaces. This interfacial mixing affects the magnetic properties. The basic difference between the two systems is the fact that while Fe-Ni interfacial alloys are magnetically soft those of Fe-Co are hard which leads to different magnetic behavior. Furthermore, the Fe layers are better crystallized in our samples than those prepared by rf magnetron or ion-beam sputtering.