Effect of interfacial structures on spin dependent tunneling in epitaxial L 10-FePt/MgO/FePt perpendicular magnetic tunnel junctions

G. Yang, D. L. Li, S. G. Wang*, Q. L. Ma, S. H. Liang, H. X. Wei, X. F. Han, T. Hesjedal, R. C.C. Ward, A. Kohn, A. Elkayam, N. Tal, X. G. Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Epitaxial FePt(001)/MgO/FePt magnetic tunnel junctions with L10-FePt electrodes showing perpendicular magnetic anisotropy were fabricated by molecular beam epitaxial growth. Tunnel magnetoresistance ratios of 21% and 53% were obtained at 300 K and 10 K, respectively. Our previous work, based on transmission electron microscopy, confirmed a semi-coherent interfacial structure with atomic steps (Kohn et al., APL 102, 062403 (2013)). Here, we show by x-ray photoemission spectroscopy and first-principles calculation that the bottom FePt/MgO interface is either Pt-terminated for regular growth or when an Fe layer is inserted at the interface, it is chemically bonded to O. Both these structures have a dominant role in spin dependent tunneling across the MgO barrier resulting in a decrease of the tunneling magnetoresistance ratio compared with previous predictions.

Original languageEnglish
Article number083904
JournalJournal of Applied Physics
Volume117
Issue number8
DOIs
StatePublished - 28 Feb 2015
Externally publishedYes

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