Barrier dependence of magnetoresistance enhancement in nano-oxide added spin valves

The effects of different types of nano-oxides on the properties of spin valves have been studied. The nano-oxides that have been investigated in this study include NiFe–O, Al–O, CoFe–O, Ta–O, and Cu–O. From the point of view of overall properties (magnetoresistance ratio, change of sheet resistance, exchange coupling field, and interlayer coupling field), CoFe–O turned out to be the most desirable oxide when being used as the bottom oxide for top spin valves. As a capping layer for bottom spin valves, however, it was found that Al–O is the best choice among those investigated. Under optimum conditions, IrMn-based dual spin valves with a magnetoresistance ratio up to 21.8% has been successfully fabricated by incorporating oxide layers in both pinned ferromagnetic layers.

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