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Magnetism of Site Random Model - Coexistence of Ferromagnetism and Antiferromagnetism -

Research Project

Project/Area Number 09640452
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 物性一般(含基礎論)
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

MATSUBARA Fumitaka  Graduate School of Engineering, Tohoku University, Professor, 大学院・工学研究科, 教授 (90124627)

Co-Investigator(Kenkyū-buntansha) SHIRAKURA Takayuki  Humanity and Social Science, Iwate University, Associate Professor, 人文社会科学部, 助教授 (90187534)
SUZUKI Nobuo  Graduate School of Engineering, Tohoku University, Research Assistant, 大学院・工学研究科, 助手 (30302186)
NAKAMURA Tohta  Graduate School of Engineering, Tohoku University, Research Assistant, 大学院・工学研究科, 助手 (50280871)
Project Period (FY) 1997 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
KeywordsSite-Random / Spin-Glass / Mesoscopic Magnetic Films / Dipole Interaction / Monte Carlo / Cluster Heat Bath / メゾスコピック磁性体 / 不純物効果 / リエントラント
Research Abstract

1. Low Temperature Phase of Spin Glasses
We have proposed a new method for evaluating the defect energy of spin glass models on finite lattices. Using the method, we have reexamined the stability of the spin glass phase of two models, the Ising model in two dimensions and the Heisenberg model in three dimensions. For both the models, the defect energy increases with the size of the lattice, suggesting the occurrence of a finite temperature phase transition. These results disprove the previous idea that the spin glass phase is realized only in the Ising model in three dimensions.
2. New Simulation Algorithm
We have developed two simulation methods, a cluster heat bath (CHB) method and a discrete update Monte Carlo method. The former method is a hybridized one of an analytic method and a stochastic method, and very effective for studying complex systems. The latter method is one for systems with long-range interactions and used for studying the spin structure of mesoscopic systems.
3. Spin Structure of Mesoscopic Ultrathin Magnetic Films
We have studied magnetic properties of micron- and submicron-scale ultrathin ferromagnetic films with uniaxial anisotropy using a discrete update Monte Carlo method. We have found that those films exhibits different magnetic properties depending on their lattice size. In small lattices, the films exhibit properties similar to those of a usual ferromagnet. In moderate lattices, the specific heat exhibits a double peak and the magnetization increases abruptly around the lower peak temperature. In large lattices, the magnetization does not increase but the specific heat still exhibits a double peak.

Report

(4 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • 1997 Annual Research Report
  • Research Products

    (18 results)

All Other

All Publications (18 results)

  • [Publications] A.Sato,F.Matsubara: "Equilibrium properties of an axial next-nearest-neighbor Ising model in two dimensions"Physical Review B. 60・14. 10316-10324 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] J.Sasaki,F.Matsubara: "Magnetic Properties of Mesoscopic Ultrathin Magnetic Films with Uniaxial Anisotropy"Journal of Applied Physics. (印刷中). (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] O.Koseki,F.Matsubara: "Monte Carlo Simulation of Magnetic Ordering of Quasi-One Dimensional Ising Antiferromagnets C_SO_OB_r_3 and C_SC_OCl_3"Journal of Physical society of Japan. (印刷中). (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] A. Sato and F. Matsubara: "Equilibrium properties of an axial next-nearest-neighbor Ising model in two dimensions"Physical Review B. Vol. 60, No. 14. 10316-10324 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Osamu Koseki and Fumitaka Matsubara: "Monte Carlo Simulation of Magnetic Ordering of Quasi-One Dimensional Ising Antiferromagnets CsCoBrィイD23ィエD2 and CsCoClrィイD23ィエD2"Journal of the Physical Society of Japan. (in press). (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] J. Sasaki and F. Matsubara: "Magnetic Properties of Mesoscopic Ultrathin Magnetic Films with Uniaxial Anisotropy"Journal of Applied Physics. (in press). (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Akiko Sato: "Equilibrium properties of an axial next-nearest-neighbor Ising model in two dimensions"Physical Review B. 60・14. 10316-10324 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] Junya Sasaki: "Magnetic Properties of Mesoscopic Ultrathin Magnetic Films with Uniaxial Anisotropy"Journal of Applied Physics. (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] Osamu Koseki: "Monte Carlo Simulation of Magnetic Ordering of Quasi-One Dimensional Ising Antiferromagnets CsCoBr_3 and CsCoCl_3"Journal of Physical Society of Japan. (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] Junya Sasaki: "Chiral Vector Phase of a Two-Dimensional Antifer romagnet with Dipolar Interactions on the Trianaular Lattice" Journal of the Physical Society of Japan. 67・4. 1134-1137 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] Nobuo Suzuki: "Thermodynamic Properties of the quantum antiferromagnet on the triangular lattie in a magnetic tield" Physical Review B. 58・9. 5169-5172 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] Fumitaka Matsubara: "Detect energy with conjugate boundery canditions in spin-glass models in Two dimensions" Physical Review B. 58・18. RII821-RII823 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] Nobuo Suzuki: "Phase diagram of the S=1/2quantum antiferromagnetic XY model on the trianglar lattice in magnetic field" Physical Review B. 55・18. 12331-12337 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Osamu Koseki: "Cluster Heat Bath Method and Quasi-One-Dimensional Ising Model" Journal of the Physical Society of Japan. 66・2. 322-325 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Fumitaka Matsubara: "Cluster Heat Bath Algorithm in Monte Carlo Simulation" Physical Review Letters. 78・17. 3237-3240 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Junya Sasaki: "Circular Phase of a Two-Dimensional Ferromagnet with Dipolar Interactions" Journal of the Physical Society of Japan. 66・7. 2138-2146 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Takayuki Shirakura: "Low Temperature Phase of Asymmetric Spin Glass Model in Two Dimensions" Physical Review Letters. 79・15. 2887-2890 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Makoto Ohshima: "Inpurity Effect on Magnetic Ordering of Quasi-One Dimensional Ising Antiferro Magnets CsCoCl_3 and CsCoBr_3" Journal of the Physical Society of Japan. 67・3. 984-985 (1998)

    • Related Report
      1997 Annual Research Report

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Published: 1998-04-01   Modified: 2016-04-21  

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