The exchange coupling of a NiO/FeNi bilayer withinterdiffused interface

Abstract

A series of NiO(110 Å)/FeNi(tF Å)/Cu(24 Å)/FeNi(tF Å)spin-valve-structure samples were fabricated using ion beamsputtering. The exchange bias HE of the pinned FeNi layerincreases as the FeNi thickness tF decreases. For tF<70 Å, however, HE decreases with the decrease of tF.The coercivity HCp varies as 1/tF at room temperature.The M-H loops show that the magnetic moment of the pinned FeNilayer is smaller than that of the free FeNi layer, indicating thatan FeNi layer of about 20 Å is interdiffused with the NiO layerleading to a drop of the magnetic moment of the pinned FeNi layer. Theinterdiffusion between the FeNi and NiO layers may account for thedecrease of the exchange bias HE for tF<70 Å.