Investigation on the exchange coupling properties of ring-shaped MnIr/CoFe bilayers

C. C. Chen, M. H. Shiao, Y. C. Lin, H. M. Tsai, C. Y. Kuo, Lance Horng, J. C. Wu, S. Isogami, M. Tsunoda, M. Takahashi

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In this study, the exchange coupling properties of submicron patterned MnIr/CoFe bilayers with strong exchange coupling strength were investigated. The large area of 2.5 mm,×, 2.5 mm of submicron sized bilayer rings were fabricated by electron beam lithography and ion-milling processes. The clear variations of normalized magnetic hysteresis loops of patterned films are the degradation of pinned CoFe at the MnIr/CoFe interfaces and the decrease of exchange bias field, comparing with sheet film. After post-field-annealing treatment, only the exchange field was improved. A magnetic tunnel junction ring with outer diameter/linewidth of 2/0.5 μm was constructed as well to further certify the speculations. The magnetoresistance loops of as-fabricated and post-field annealed MTJ ring revealed that the slightly improved magnetoresistance ratio and exchange field. These results were attributed to the rearrangement of distorted spins at the sample edges. However, in comparison with sheet film, the great degradation of magnetoresistance ratio of patterned device, without respect to as-fabricated or post-field annealed, was not retrieved, revealing that the futility of post-field-annealing treatment to the pinning portion of CoFe layer.

Original languageEnglish
Article number5721802
Pages (from-to)620-623
Number of pages4
JournalIEEE Transactions on Magnetics
Volume47
Issue number3
DOIs
Publication statusPublished - 2011 Mar 1

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Exchange coupling
Magnetoresistance
Annealing
Magnetic hysteresis
Degradation
Tunnel junctions
Electron beam lithography
Hysteresis loops
Linewidth
Ions

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this

Chen, C. C. ; Shiao, M. H. ; Lin, Y. C. ; Tsai, H. M. ; Kuo, C. Y. ; Horng, Lance ; Wu, J. C. ; Isogami, S. ; Tsunoda, M. ; Takahashi, M. / Investigation on the exchange coupling properties of ring-shaped MnIr/CoFe bilayers. In: IEEE Transactions on Magnetics. 2011 ; Vol. 47, No. 3. pp. 620-623.
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Chen, CC, Shiao, MH, Lin, YC, Tsai, HM, Kuo, CY, Horng, L, Wu, JC, Isogami, S, Tsunoda, M & Takahashi, M 2011, 'Investigation on the exchange coupling properties of ring-shaped MnIr/CoFe bilayers', IEEE Transactions on Magnetics, vol. 47, no. 3, 5721802, pp. 620-623. https://doi.org/10.1109/TMAG.2010.2100370

Investigation on the exchange coupling properties of ring-shaped MnIr/CoFe bilayers. / Chen, C. C.; Shiao, M. H.; Lin, Y. C.; Tsai, H. M.; Kuo, C. Y.; Horng, Lance; Wu, J. C.; Isogami, S.; Tsunoda, M.; Takahashi, M.

In: IEEE Transactions on Magnetics, Vol. 47, No. 3, 5721802, 01.03.2011, p. 620-623.

Research output: Contribution to journalArticle

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T1 - Investigation on the exchange coupling properties of ring-shaped MnIr/CoFe bilayers

AU - Chen, C. C.

AU - Shiao, M. H.

AU - Lin, Y. C.

AU - Tsai, H. M.

AU - Kuo, C. Y.

AU - Horng, Lance

AU - Wu, J. C.

AU - Isogami, S.

AU - Tsunoda, M.

AU - Takahashi, M.

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N2 - In this study, the exchange coupling properties of submicron patterned MnIr/CoFe bilayers with strong exchange coupling strength were investigated. The large area of 2.5 mm,×, 2.5 mm of submicron sized bilayer rings were fabricated by electron beam lithography and ion-milling processes. The clear variations of normalized magnetic hysteresis loops of patterned films are the degradation of pinned CoFe at the MnIr/CoFe interfaces and the decrease of exchange bias field, comparing with sheet film. After post-field-annealing treatment, only the exchange field was improved. A magnetic tunnel junction ring with outer diameter/linewidth of 2/0.5 μm was constructed as well to further certify the speculations. The magnetoresistance loops of as-fabricated and post-field annealed MTJ ring revealed that the slightly improved magnetoresistance ratio and exchange field. These results were attributed to the rearrangement of distorted spins at the sample edges. However, in comparison with sheet film, the great degradation of magnetoresistance ratio of patterned device, without respect to as-fabricated or post-field annealed, was not retrieved, revealing that the futility of post-field-annealing treatment to the pinning portion of CoFe layer.

AB - In this study, the exchange coupling properties of submicron patterned MnIr/CoFe bilayers with strong exchange coupling strength were investigated. The large area of 2.5 mm,×, 2.5 mm of submicron sized bilayer rings were fabricated by electron beam lithography and ion-milling processes. The clear variations of normalized magnetic hysteresis loops of patterned films are the degradation of pinned CoFe at the MnIr/CoFe interfaces and the decrease of exchange bias field, comparing with sheet film. After post-field-annealing treatment, only the exchange field was improved. A magnetic tunnel junction ring with outer diameter/linewidth of 2/0.5 μm was constructed as well to further certify the speculations. The magnetoresistance loops of as-fabricated and post-field annealed MTJ ring revealed that the slightly improved magnetoresistance ratio and exchange field. These results were attributed to the rearrangement of distorted spins at the sample edges. However, in comparison with sheet film, the great degradation of magnetoresistance ratio of patterned device, without respect to as-fabricated or post-field annealed, was not retrieved, revealing that the futility of post-field-annealing treatment to the pinning portion of CoFe layer.

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