Abstract
The structural and magnetic properties of NiCo (Ni,Co) O bilayers were investigated. X-ray diffractometry results have shown that the top NiCo layer consisted of a fcc NiCo phase. The bilayer bottom was either a pure (Ni,Co)O or a composite [NiCo+ (Ni,Co) O] phase, depending on the percent of O2 Ar ratio used during deposition. A double-shifted hysteresis loop exhibiting components that were from positive or negative coupling was observed in the NiCo (Ni,Co) O (8% O2 Ar) bilayers. The microstructural changes, which result from a combination of deposition oxygen content and the ion-beam bombardment, will result in the unusual exchange bias behavior. © 2008 American Institute of Physics.