Characterization of nano-oxide layer in specular spin valve multilayer

To characterize the nano-oxide layer (NOL) in specular spin valve multilayer, naturally oxidized CoFe layer was inserted between pinned CoFe layers. The under-, optimum, and over-oxidized samples were obtained by control of the oxidation time and the oxygen flow rate. The NOL was analyzed to be Fe oxide mainly by X-ray photoelectron spectroscopy (XPS) data. As oxidation increased, the content of Fe oxide and the thickness of the NOL increased and too much thicker NOL was obtained in case of over-oxidation. We concluded that the lower magnetoresistance (MR) ratio and the more slanted magnetization curve than the optimum could be attributed to the Fe oxide as a non-ferromagnetic defect or magnetic discontinuity in case of under-oxidation and the too thick NOL in case of over-oxidation.