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Development of New Magnetic Sensor Utilizing the PMR Effect of Half-Metallic Ferromagnetic Powders

Research Project

Project/Area Number 16360200
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Measurement engineering
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

TSUNODA Masakiyo  Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (80250702)

Project Period (FY) 2004 – 2005
Project Status Completed (Fiscal Year 2005)
Budget Amount *help
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2005: ¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 2004: ¥6,400,000 (Direct Cost: ¥6,400,000)
KeywordsChromium Dioxide / Half Metals / Tunnel Magnetoresistance Effect / PMR Effect / Cold Press / Mechanical Alloying
Research Abstract

Chromium dioxide (CrO_2) is expected to be a strong spin polarizer in forthcoming spinelectronics devices, since it has been theoretically predicted as a half-metallic material on one hand and nearly perfect spin polarization has been experimentally demonstrated on the other. In cold-pressed CrO_2 powder compacts, large magnetoresistance (MR) that originates due to the intergranular spin dependent tunneling was observed at low temperatures. However, the relatively low Curie temperature of CrO_2 (T_c 〜 400 K) prevents it from being used in device applications. Elevating the Curie temperature of CrO_2 is indispensable factor to realize powder magnetoresistance (PMR) sensors for room temperature application.
The present authors have succeeded in synthesizing CrO_2 powders through mechanochemical method, and doping was easily achieved by introducing the dopant as raw material. Thus, in the present study, we investigated the influence of doping elements and their concentration on the magnetic and magnetotransport properties of CrO_2 powder compacts. The (Cr-M)O_2 (M=V,Mn,Fe,Co) powders were synthesized by the mechanochemical method and the magnetoresistance (MR) effect of their powder compacts was investigated as a function of the type and content of the dopant. The findings are summarized below. Substituting limit of M for Cr in CrO_2 was 30 at% for V, Mn, and Co, and 5 at% for Fe. Doping with V effectively decreases the T_c, while Fe significantly elevates the same (420 K with 5 at% Fe). Furthermore, the changes observed in the cases of Co and Mn was marginal. MR ratio was significantly enhanced up to 22% at 4.2 K with the doping of 5 at% of Fe, however, decreased in the cases of V and Co doping. The reason for the MR enhancement in (Cr-Fe)O_2 powder compacts is due to the change in the barrier characteristics.

Report

(3 results)
  • 2005 Annual Research Report   Final Research Report Summary
  • 2004 Annual Research Report
  • Research Products

    (6 results)

All 2005 2004

All Journal Article (6 results)

  • [Journal Article] Intergranular Tunneling Magnetoresistance of Mechanically Alloyed (Cr-M)O_2 Powder Compacts2005

    • Author(s)
      M.Tsunoda
    • Journal Title

      IEEE Transactions on Magnetics 41巻10号

      Pages: 3400-3402

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] Intergranular Tunneling Magnetoresistance of Mechanically Alloyed (Cr-M)O_2 Powder Compacts2005

    • Author(s)
      M.Tsunoda
    • Journal Title

      IEEE Transactions on Magnetics 41(10)

      Pages: 3400-3402

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] Intergranular Tunneling Magnetoresistance of Mechanically Alloyed (Cr-M) O_2 Powder Compacts2005

    • Author(s)
      M.Tsunoda
    • Journal Title

      IEEE Transactions on Magnetics 41(10)

      Pages: 3400-3402

    • Related Report
      2005 Annual Research Report
  • [Journal Article] メカニカルアロイング法によって作製した(Cr-M)O_2粉末のPMR効果2004

    • Author(s)
      佐藤哲也
    • Journal Title

      日本応用磁気学会誌 28巻

      Pages: 360-363

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] PMR Effect of (Cr-M)O_2 Powder Prepared by Mechanical Alloying2004

    • Author(s)
      T.Sato
    • Journal Title

      Journal of Magnetic Society of Japan 28

      Pages: 360-363

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] メカニカルアロイング法によって作製した(Cr-M)O_2粉末のPMR効果2004

    • Author(s)
      佐藤哲也
    • Journal Title

      日本応用磁気学会誌 28巻3号

      Pages: 360-363

    • Related Report
      2004 Annual Research Report

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Published: 2004-04-01   Modified: 2016-04-21  

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