Enhanced magnetoresistance in naturally oxidized MgO-based magnetic tunnel junctions with ferromagnetic CoFe/CoFeB bilayers

D. K. Schreiber, Y. S. Choi, Yuzi Liu, Ann N. Chiaramonti, David N. Seidman, A. K. Petford-Long

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Three-dimensional elemental distributions in magnetic tunnel junctions containing naturally oxidized MgO tunnel barriers are characterized using atom-probe tomography. Replacing the CoFeB free layer (reference layer) with a CoFe/CoFeB (CoFeB/CoFe) bilayer increases the magnetoresistance from 105% to 192% and decreases the resistance-area product from 14.5 to 3.4 μm 2. The CoFe/CoFeB bilayer improves the compositional uniformity within the free layer by nucleating CoFeB crystals across the entire layer, resulting in a homogeneous barrier/free layer interface. In contrast, the simple CoFeB free layer partially crystallizes with composition differences from grain to grain (5-30 nm), degrading the tunnel junction performance.

Original languageEnglish (US)
Article number232506
JournalApplied Physics Letters
Volume98
Issue number23
DOIs
StatePublished - Jun 6 2011

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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