Epitaxial all-bcc-Co50Fe50/Cu/Co50Fe50 current-in-plane giant magnetoresistive spin-valves on Si(0 0 1) substrate

Abstract

Following the high magnetoresistance (MR) ratio reported for fully epitaxial CoFe/bcc-Cu/CoFe current-in-plane giant magnetoresistance (CIP-GMR) grown on MgO(001) single crystalline substrate, we attempted to grow epitaxial CoFe/bcc-Cu/CoFe CIP-GMR devices on industrially viable Si(001) substrate through an epitaxial NiAl buffer layer. We found that the deposition of MgO insulation layer on the NiAl buffer layer is crucial to prevent current shunting in the NiAl layer which reduces MR ratio. The epitaxial CIP-GMR device grown on Si(001) exhibited sufficiently high MR ratio up to 15.9(±0.1)% at room temperature; however, it is somehow lower than that grown on the MgO(001) substrate, 20.6(±0.1)%. Detailed microstructural analysis revealed that fcc phase of Cu presented in the bcc-Cu spacer, which is considered to be the reason for the lower MR ratio of the device grown on Si(001) substrate.