Magnetoresistance Effect and XPS Study of Fe/CeO₂/Fe-Co Tunnel Junctions

Abstract

A series of Fe/CeO₂/Fe-Co tunnel junctions with CeO₂ barrier layers ranging from 30 to 90 Å in thickness were prepared by ion beam sputtering (IBS). Some Fe/Al oxide/Fe-Co tunnel junctions were also made, to compare the junction properties. The interface of the Fe/CeO₂ bilayer was investigated by means of X-ray photoelectron spectroscopy (XPS). Some junctions with a CeO₂ barrier layer showed the ferromagnetic tunneling effect. The resistance of junctions with a CeO₂ barrier layer was higher than that of junctions with an Al oxide barrier. CeO₂ was decomposed into Ce and O₂ by sputtering, and Fe was oxidized by sputtering O₂ molecules on the substrate. The remaining Ce in the barrier layer reduced the junction resistance.