Detection of bottom ferromagnetic electrode oxidation in magnetic tunnel junctions by magnetometry measurements

Journal Article · Wed Dec 01 04:00:00 EST 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3518506· OSTI ID:21537965

Wei, Chen ^[1]; Nam, Dao N. H.; Lu, Jiwei ^[2]; Wolf, Stuart A ^[1]

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1. Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States)
2. Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

Surface oxidation of the bottom ferromagnetic (FM) electrode, one of the major detrimental factors to the performance of a magnetic tunnel junction (MTJ), is difficult to avoid during the fabrication process of the MTJ's tunnel barrier. Since Co rich alloys are commonly used for the FM electrodes in MTJs, overoxidation of the tunnel barrier results in the formation of a CoO antiferromagnetic (AF) interface layer which couples with the bottom FM electrode to form a typical AF/FM exchange bias (EB) system. In this work, surface oxidation of the CoFe and CoFeB bottom electrodes was detected via magnetometry measurements of EB characterizations including the EB field, training effect, uncompensated spin density, and enhanced coercivity. Variations in these parameters were found to be related to the surface oxidation of the bottom electrode, among them the change in coercivity is most sensitive. Annealed samples show evidence for an oxygen migration back to the MgO tunnel barrier by annealing.

• OSTI ID: 21537965
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 108; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ANGULAR MOMENTUM
ANNEALING
ANTIFERROMAGNETIC MATERIALS
ANTIFERROMAGNETISM
BORON ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
COBALT ALLOYS
COBALT COMPOUNDS
COBALT OXIDES
COERCIVE FORCE
ELECTRODES
FERROMAGNETIC MATERIALS
HEAT TREATMENTS
INTERFACES
IRON ALLOYS
LAYERS
MAGNETIC MATERIALS
MAGNETISM
MAGNETOMETERS
MATERIALS
MEASURING INSTRUMENTS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
SPIN
SURFACES
TRANSITION ELEMENT ALLOYS
TRANSITION ELEMENT COMPOUNDS
TUNNEL EFFECT