Conceptual material design for magnetic tunneling junction cap layer for high magnetoresistance ratio

The magnetoresistance ratio (MR) and resistance area product (RA) of cap/NiFe/Al[O.sub.x] /CoFe stack with several cap layers are investigated and a model explaining correlation between MR ratio and RA and the cap layer material is proposed, in a viewpoint of the standard electrode potential. The highest MR ratio with nonmagnetic-NiFeZr cap is consistent with the lowest electrode potential of Zr, and it is believed that non-magnetic-NiFeZr cap realizes a steep NiFe/AlOx interface without the oxidation of NiFe.