Superparamagnetism in MgO-based magnetic tunnel junctions with a thin pinned ferromagnetic electrode

J. F. Feng; J. Y. Chen; M. Venkatesan; G. Feng; X. F. Han; J. M.D. Coey

doi:10.1103/PhysRevB.81.205212

Superparamagnetism in MgO-based magnetic tunnel junctions with a thin pinned ferromagnetic electrode

J. F. Feng, J. Y. Chen, M. Venkatesan, G. Feng, X. F. Han, J. M.D. Coey

Electrical and Computer Engineering

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

15 Scopus citations

Abstract

MgO-based magnetic tunnel junctions have been fabricated with a thin Co₄₀ Fe₄₀ B₂₀ (CoFeB) layer in the pinned synthetic antiferromagnetic CoFe/Ru/CoFeB stack. An inverted tunneling magnetoresistance is observed due to the unbalanced synthetic antiferromagnet. Superparamagnetic nanoparticles form when the CoFeB layer is thinner than 1.5 nm, and an abnormal temperature dependence of the junction resistance is associated with superparamagnetism when the thermal fluctuation energy exceeds the magnetic anisotropy energy. This explanation accounts for the temperature dependence of the tunneling magnetoresistance effect.

Original language	English (US)
Article number	205212
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	81
Issue number	20
DOIs	https://doi.org/10.1103/PhysRevB.81.205212
State	Published - May 25 2010

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10.1103/PhysRevB.81.205212

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title = "Superparamagnetism in MgO-based magnetic tunnel junctions with a thin pinned ferromagnetic electrode",

abstract = "MgO-based magnetic tunnel junctions have been fabricated with a thin Co40 Fe40 B20 (CoFeB) layer in the pinned synthetic antiferromagnetic CoFe/Ru/CoFeB stack. An inverted tunneling magnetoresistance is observed due to the unbalanced synthetic antiferromagnet. Superparamagnetic nanoparticles form when the CoFeB layer is thinner than 1.5 nm, and an abnormal temperature dependence of the junction resistance is associated with superparamagnetism when the thermal fluctuation energy exceeds the magnetic anisotropy energy. This explanation accounts for the temperature dependence of the tunneling magnetoresistance effect.",

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AU - Feng, J. F.

AU - Chen, J. Y.

AU - Venkatesan, M.

AU - Feng, G.

AU - Han, X. F.

AU - Coey, J. M.D.

PY - 2010/5/25

Y1 - 2010/5/25

N2 - MgO-based magnetic tunnel junctions have been fabricated with a thin Co40 Fe40 B20 (CoFeB) layer in the pinned synthetic antiferromagnetic CoFe/Ru/CoFeB stack. An inverted tunneling magnetoresistance is observed due to the unbalanced synthetic antiferromagnet. Superparamagnetic nanoparticles form when the CoFeB layer is thinner than 1.5 nm, and an abnormal temperature dependence of the junction resistance is associated with superparamagnetism when the thermal fluctuation energy exceeds the magnetic anisotropy energy. This explanation accounts for the temperature dependence of the tunneling magnetoresistance effect.

AB - MgO-based magnetic tunnel junctions have been fabricated with a thin Co40 Fe40 B20 (CoFeB) layer in the pinned synthetic antiferromagnetic CoFe/Ru/CoFeB stack. An inverted tunneling magnetoresistance is observed due to the unbalanced synthetic antiferromagnet. Superparamagnetic nanoparticles form when the CoFeB layer is thinner than 1.5 nm, and an abnormal temperature dependence of the junction resistance is associated with superparamagnetism when the thermal fluctuation energy exceeds the magnetic anisotropy energy. This explanation accounts for the temperature dependence of the tunneling magnetoresistance effect.

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Superparamagnetism in MgO-based magnetic tunnel junctions with a thin pinned ferromagnetic electrode

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