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

doi:10.1063/1.3597224

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

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

12 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 language	English (US)
Article number	232506
Journal	Applied Physics Letters
Volume	98
Issue number	23
DOIs	https://doi.org/10.1063/1.3597224
State	Published - Jun 6 2011

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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10.1063/1.3597224

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@article{91fc836a2d704267a03ed390b83ec5be,

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

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.",

author = "Schreiber, {D. K.} and Choi, {Y. S.} and Yuzi Liu and Chiaramonti, {Ann N.} and Seidman, {David N.} and Petford-Long, {A. K.}",

note = "Funding Information: The authors acknowledge UChicago Argonne, LLC, operator of Argonne National Laboratory, a Department of Energy, Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357, the Electron Microscopy Center and the Center for Nanoscale Materials. APT measurements were performed in the Northwestern University Center for Atom-Probe Tomography with funding from NSF-MRI (DMR-0420532) and ONR-DURIP grants (N00014-0400798, N00014-0610539, N00014-0910781). ",

year = "2011",

month = jun,

day = "6",

doi = "10.1063/1.3597224",

language = "English (US)",

volume = "98",

journal = "Applied Physics Letters",

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publisher = "American Institute of Physics",

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AU - Schreiber, D. K.

AU - Choi, Y. S.

AU - Liu, Yuzi

AU - Chiaramonti, Ann N.

AU - Seidman, David N.

AU - Petford-Long, A. K.

N1 - Funding Information: The authors acknowledge UChicago Argonne, LLC, operator of Argonne National Laboratory, a Department of Energy, Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357, the Electron Microscopy Center and the Center for Nanoscale Materials. APT measurements were performed in the Northwestern University Center for Atom-Probe Tomography with funding from NSF-MRI (DMR-0420532) and ONR-DURIP grants (N00014-0400798, N00014-0610539, N00014-0910781).

PY - 2011/6/6

Y1 - 2011/6/6

N2 - 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.

AB - 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.

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

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