Effect of NiO sputtering condition to the exchange anisotropy of NiFe/NiO bilayer

Summary form only given, as follows. Summary form only given. As an application for spin-valve type giant magnetoresistance (GMR) devices, exchange biased NiFe/NiO bilayers have been studied extensively. The current study focuses on the formation of a second phase at the NiO layer and resultant change of the exchange anisotropy in the bilayers. The NiFe/NiO bilayers were deposited on silicon wafers by sputtering and a Ta capping was applied on the bilayer. Target materials were Ni/sub 81/Fe/sub 19/ alloy and NiO oxide. Ar pressure effects on the magnetic properties of the NiO film were studied under constant conditions of input power and film thickness. Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS) were used to investigate the composition and the chemical state of the NiO film. The magnetic properties of NiO changed with Ar pressure. The exchange bias field (Hex) shows a maximum at 1 mTorr Ar pressure and the coercivity at 2.5 mTorr. The antiferromagnetism of NiO was destroyed gradually with increasing Ar pressure This destruction of antiferromagnetism occurs mainly at the interface of NiO and NiFe, due to the formation of an amorphous phase. RBS results show that there are two Ni oxide phases, antiferromagnetic NiO and nonmagnetic Ni/sub 2/O/sub 3/. We conclude that the amorphous Ni/sub 2/O/sub 3/ phase results in the destruction of exchange anisotropy of NiFe/NiO bilayers.