MgO障壁を用いたFePt垂直磁化トンネル磁気抵抗素子の磁気抵抗特性および極微構造

概要

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Perpendicularly magnetized magnetic tunnel junctions (MTJs) were fabricated by depositing thin L10-ordered FePt films on MgO(001) substrates using a UHV sputtering system, and the dependence of structural, magnetic, and magnetotransport properties of the junctions on the thickness of the FePt layers was investigated. A full epitaxial structure of MgO(001) sub./Cr/Pt/FePt/MgO/CoPt/Ta was observed. The tunnel magnetoresistance (TMR) ratio was measured to be 6% at room temperature, and magnetization switching was clearly observed in the thin FePt layer. Transmission electron microscopy (TEM) observations revealed that the interface between FePt, MgO, and CoPt layer has strain due to lattice mismatch, which might be a reason for the low TMR ratio.