X-ray photoelectron spectroscopy and magnetic force microscopy studies of ion-beam deposited Ni/sub 80/Fe/sub 20//Co-oxide bilayers

The correlation between the structural and magnetic properties in Ni/sub 80/Fe/sub 20//Co-oxide bilayers that were prepared using a dual-ion beam deposition technique has been investigated. The pure Permalloy (Ni/sub 80/Fe/sub 20/) film (a = 3.53 /spl Aring/) consisted of face-centered cubic nanocrystallites. Films prepared with 8% O/sub 2/ and 34% O/sub 2/ in the assist beam consisted of rock-salt CoO (a = 4.27 /spl Aring/) and spinel Co/sub 3/O/sub 4/ (a = 8.21 /spl Aring/). The composition and oxidation state of the Co-oxide layers were analyzed with X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), and transmission electron microscopy (TEM). Magnetic force microscopy (MFM) revealed that the Ni/sub 80/Fe/sub 20//Co bilayer exhibited ripple domains, whereas cross-tie domain walls were found in Ni/sub 80/Fe/sub 20//CoO bilayer. At 289 K, the pure Permalloy film exhibited soft magnetic properties while a magnetic hardening with enhanced coercivity was observed in the Ni/sub 80/Fe/sub 20//CoO bilayer. Additionally, the Ni/sub 80/Fe/sub 20//CoO bilayer exhibited an exchange shift H/sub ex//spl sim/-75 Oe at 150 K.