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Tunnel magnetoresistance in Fe/MgO/Fe junctions -toward application of MRAM-

Research Project

Project/Area Number 17560008
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Applied materials science/Crystal engineering
Research InstitutionNagoya University

Principal Investigator

ITOH Hiroyoshi  Nagoya University, Graduate School of Engineering, Research Associate, 大学院工学研究科, 助手 (00293671)

Project Period (FY) 2005 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywordsspin-electronics / tunnel junction / magnetoresistance / TMR / spin-filter
Research Abstract

A large tunnel magnetoresistancce (TMR) as large as 400% has been observed at room temperature in Fe/MgO/Fe junctions. Since the momentum and symmetry of the Bloch states are conserved in eitaxial junctions, MgO serves as momentum-and symmetry-filters. Furthermore, delta-1 band of Fe is half-metallic and, then, MgO is a spin-filter in epitaxial Fe/MgO/Fe junctions, which results in large TMR. However, the effect of disorder on the TMR is not fully understood yet. Ferromagnetic insulator also serves as a spin-filter in different mechanism from MgO. In this work, TMR and spin-filter effect in magnetic tunnel junctions are studied by using numerical simulations based on the linear response theory.
In Fe/MgO/Fe junction, TMR is calculated for both clean and disordered systems. Large TMR obtained in clean junctions is attributed to the momentum and symmetry-filter effect of MgO barrier as already shown. It has been found that lattice distortions within MgO and at the interfaces decrease the MR ratio because the disorder weakens the filter effects and causes hybridization between Bloch wave functions having different momenta and symmetries.
The spin-filter effect in junctions containing a ferromagnetic insulator LaNi_<0.5>Mn_<0.5>O_3 has been also investigated. It has been shown that a large spin-filter effect is obtained in LaNiO_3/LaNi_<0.5>Mn_<0.5>O_3/LaNiO_3 junctions although the tunnel barrier height is spin independent. Therefore, in (La-Sr)MnO_3/ LaNiO_3/LaNi_<0.5>Mn_<0.5>O_3/LaNiO_3 junctions, TMR much larger than that observed in Fe/MgO/Fe junctions is expected.

Report

(3 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • Research Products

    (18 results)

All 2007 2006 2005

All Journal Article (18 results)

  • [Journal Article] Theory of tunnel magnetoresistance and spin-filter effect in magnetic tunnel junctions2007

    • Author(s)
      H.Itoh
    • Journal Title

      Journal of Physics D : Applied Physics 40

      Pages: 1228-1233

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Electronic structure and spin-filter effect of ferromagnetic insulators with double perovskite structure2007

    • Author(s)
      H.Itoh, J.Ozeki, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Materials 310

      Pages: 1994-1996

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] Interfacial electronic structure and oxygen vacancy states in Fe/MgO/Fe tunneling junctions2007

    • Author(s)
      J.Ozeki, H.Itoh, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Materials 310

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Theory of tunnel magnetoresistance and spin-filter effect in magnetic tunnel junctions2007

    • Author(s)
      H.Itoh
    • Journal Title

      Journal of Physics D : Applied Physics vol.40

      Pages: 1228-1233

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Electronic structure and spin-filter effect of ferro-magnetic insulators with double perovskite structure2007

    • Author(s)
      H.Itoh, J.Ozeki, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Material vol.310

      Pages: 1994-1996

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Interfacial electronic structure and oxygen vacancy states in Fe/MgO/Fe tunneling junctions2007

    • Author(s)
      J.Ozeki, H.Itoh, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Material vol.310

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Theory of tunnel magnetoresistance and spin filter effect in magnetic tunnel junctions2007

    • Author(s)
      Hiroyoshi Itoh
    • Journal Title

      Journal of Physics D : Applied Physics 40

      Pages: 1228-1233

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Theory of tunnel magnetoresistance2006

    • Author(s)
      H.Itoh, J.Inoue
    • Journal Title

      Journal of Magnetics Society of Japan 30

      Pages: 1-37

    • NAID

      10002546230

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Effect of disorder on tunnel magnetoresistance in Fe/MgO/Fe junctions2006

    • Author(s)
      H.Itoh, J.Ozeki, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Materials 303

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] 強磁性トンネル接合におけるスピン依存伝導の理論2006

    • Author(s)
      伊藤博介, 井上順一郎, 小瀬木淳一
    • Journal Title

      電子情報通信学会 信学技報 MR2006-5

      Pages: 25-29

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Theory of tunnel magnetoresistance2006

    • Author(s)
      H.Itoh, J.Inoue
    • Journal Title

      Journal of Magnetics Society of Japan vol.30

      Pages: 1-37

    • NAID

      10002546230

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Effect of disorder on tunnel magnetoresistance in Fe/MgO/Fe junctions2006

    • Author(s)
      H.Itoh, J.Ozeki, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Material vol.303

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Theory of spin-dependent transport in magnetic tunnel junctions2006

    • Author(s)
      H.Itoh, J.Inoue, J.Ozeki
    • Journal Title

      IEICE Technical Report vol.MR2006-5

      Pages: 25-29

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] 強磁性トンネル接合におけるスピン依存伝導の理論2006

    • Author(s)
      伊藤博介, 井上順一郎, 小瀬木淳一
    • Journal Title

      信学技報 IEICE Technical Report MR2006-5

      Pages: 25-29

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Theory of funnel magnetoresistance2006

    • Author(s)
      H.Itoh, J.Inoue
    • Journal Title

      Journal of Magnetics Society of Japan Vol.30

      Pages: 1-37

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Magnetoresistance and interlayer exchange coupling in perovskite manganite junctions2006

    • Author(s)
      J.Ozeki, T.Ohsawa, H.Itoh, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Materials (印刷中)

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Effect of disorder on tunnel magnetoresistance in Fe/MgO/Fe junctions2006

    • Author(s)
      H.Itoh, J.Ozeki, J.Inoue
    • Journal Title

      Journal of Magnetism and Magnetic Materials (印刷中)

    • Related Report
      2005 Annual Research Report
  • [Journal Article] Interlayer exchange coupling in perovskite-type magnetic trilayers2005

    • Author(s)
      T.Ohsawa, S.Kubota, H.Itoh, J.Inoue
    • Journal Title

      Physical Review B Vol.71

    • Related Report
      2005 Annual Research Report

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Published: 2005-04-01   Modified: 2016-04-21  

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