Detection of Bottom Electrode Oxidation in Magnetic Tunnel Junctions via Exchange Bias Effect

ORAL

Abstract

The oxidation of the bottom ferromagnetic (FM) electrode in a magnetic tunnel junction (MTJ) is detrimental for high tunneling magnetoresistance (TMR). This has long been a tricky problem for the fabrication of MTJs. We propose a method to detect such oxidation by measuring the exchange bias effect from the CoO/FM system if the FM surface is oxidized and CoO is formed. Along with the moderate exchange bias even more significant training effect and increased FM coercivity are observed at low temperature that depend on the oxidation level. All of these effects help in the detection of the FM surface oxidation. MTJs with MgO and vanadium oxide as tunnel barrier candidates are tested by this technique with the purpose of optimizing the barrier quality for best TMR performance.

*This work is supported by DMEA under Contract No. H94003-08-2-0803 and ONR under Contract No. N00014- 06-1-0428

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Authors

  • Kevin West

    • Department of Materials Science and Engineering, University of Virginia

  • Wei Chen

    • Department of Physics, University of Virginia

  • Nam Dao

    • Department of Materials Science and Engineering, University of Virginia, Charlottsville, VA 22904
    • Department of Materials Science and Engineering, University of Virginia
    • Department of Materials and Engineering, University of Virginia

  • David Kirkwood

    • Department of Materials Science and Engineering, University of Virginia, Charlottsville, VA 22904
    • Department of Materials Science and Engineering, University of Virginia
    • Department of Materials and Engineering, University of Virginia

  • Jiwei Lu

    • University of Virginia
    • Department of Materials Science and Engineering, University of Virginia
    • Department of Materials and Engineering, University of Virginia

  • Stuart Wolf

    • University of Virginia
    • Department of Materials Science and Engineering, University of Virginia, Charlottsville, VA 22904
    • Department of Materials Science and Engineering, University of Virginia
    • Department of Materials and Engineering and Department of Physics, University of Virginia