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Quantum Monte Carlo Study on Strongly Quantum Fluctuated Systems

Research Project

Project/Area Number 08640485
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 InstitutionOsaka University

Principal Investigator

MIYASHITA Seiji  Grad.Sch.of Sci.Osaka U., Professor, 大学院・理学研究科, 教授 (10143372)

Co-Investigator(Kenkyū-buntansha) 多々良 源  大阪大学, 大学院・理学研究科, 助手 (10271529)
Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywordsquantum phase transition / singlet pair / quantum Monte Carlo method / quantum fluctuation / itinerant ferromagnetism / flutband
Research Abstract

Systems with strong quantum fluctuation due to the stracture of lattice in order to find new peculiar properties.
The effects due to the structure of the lattice on the ordering configuration in the Heisenberg antiferromagnets are investigated. Ordering configuration means the configuration of singlet bonds which is classified with the VBS picture. In particular we investigated a chain which consists of two of S=1 spins and two of S=1/2 spins.
We also investigated effects of inhomogeneity on quantum mechanical order : effects of impurities of S=1/2 spins, and effects of dilution on the lader lattice and square lattice. In the latter project, we find so-called quantum Criffiths phase where the any correlation in the spatial direction decays exponentially but the correlation in the time axis diverges. This divergence causes the divergence of the local susceptibility.
We studied a new phase due to the quantum fluctuation in the magnetization curve in the ground state of antiferromagnetic Heisenberg model with XY anisotropy. There a collinear configuration which is unfavorite in classical case becomes stable. The transition is clearly observed by investigating the wavefunction although the transition is not clear in the changes of physical quantities.
We investigated the low temperature properties of quantum spin systems by quantum Monte Carlo method and transfer matrix method.
We found a new mechanism of the ferromagnetism in the Hubbard model and analyzed the nature of the ferromagnetism.
We started to study the dynamics of system where the quantum fluctuation has a dominant role.

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (40 results)

All Other

All Publications (40 results)

  • [Publications] Y.Watanabe,: "New Saturated Ferromagnetism in the Flat-Band Hubbard Model in High Electron Filling" J.Phys.Soc.Jpn.66. 2123-2128 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Miyashita,: "Nature of the Ordered Phase and the Critical Propertie of the Three Dimensional Six-state Clock Model" J.Phys.Soc.Jpn.66. 3411-3420 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] H.De.Raedt,: "Theory of Quantum Tunnening of the Magnetization in Magnetic Particle" Phys.Rev.B. 56. 11761-11768 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Yamamoto,: "Low-Lying Excitations in the S=1 Antiferromagnetic Heisenberg Chain" Phys.Letter A. 235. 545-550 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Y.Watanabe,: "Properties of New Saturated Ferromagnetism in the ID Flat-Band Hubbard Model as the Spiral State" J.Phys.Soc.Jpn.66. 3981-3987 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] X.Hu,: "Simulation for the First-Order Vortex-Lattice Melting Transition in High-Tc Superconductors" Physica C. 282-287. 2057-2058 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] X.Hu,: "δ-function peak in the specific heat of high-Tc Superconductors : Monte Carlo simulation" Phys.Rev.Lett.79. 3498-3501 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Miyashita,: "A Stochastic model of non-classical light emission from a micro cavity" Phys.Rev.Lett.80. 1525-1528 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] T.Tonegawa,: "One-Dimensional Heisenberg Antiferromagnets in which two S=1/2 and two S=1 spins are arranged alternatively" J.Mag.Mag.Matt.(1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] T.Tonegawa,: "Ground-State and Thermodynamic Properties of the Quantum Mixed Spin-1/2-1/2-1-1 Chain" J.Phys.Soc.Jpn. 67. (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Watarai,: "Critical Exponents of Ising-Like Heisenberg Antiferromagenets on the Hexagonal Lattice" J.Phys.Soc.Jpn.67. (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Y.Watanabe and S.Miyashita: "New Saturated Ferromagnetism in the Flat-Band Hubbard Model in High Electron Filling" J.Phys.Soc.Jpn.66. 2123-2128 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Miyashita: "Nature of the Ordered Phase and the Critical Properties of the Three Dimensional Six-state Clock Model" J.Phys.Soc.Jpn.66. 3411-3420 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] H.De Raedt, S.Miyashita, K.Saito, D.Garcia-Pablos and N.Garcia: "Theory of Quantum Tunnening of the Magnetization in Magnetic Particle" Phys.Rev.B56. 11761-11768 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Yamamoto and S.Miyashita: "Low-Lying Excitations in the S=1 Antiferromagnetic Heisenberg Chain" Phys.Letter. A235. 545-550 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Y.Watanabe and S.Miyashita: "Properties of New Saturated Ferromagnetism in the 1D Flat-Band Hubbard Model as the Spiral State" J.Phys.Soc.Jpn.66. 3981-3987 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] X.Hu, S.Miyashita and M.Tatchiki: "Simulation for the First-Order Vortex-Lattice Melting Transition in High-T_c Superconductors" Physica. C282-287. 2057-2058 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] X.Hu, S.Miyashita and M.Tatchiki: "delta-function peak in the specific heat of high-T_c Superconductors : Monte Carlo simulation" Phys.Rev.Lett.79. 3498-3501 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Miyashita, H.Ezaaki and E.Hanamura: "A Stochastic model of non-classical light emission from a micro cavity" Phys.Rev.A57. 2046-2055 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Miyashita, K.Saito and H.De Raedt: "Nontrivial resonance of nanoscale uniaxial magnets to alternating field" Phys.Rev.Lett.80. 1525-1528 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] T.Tonegawa, T.Hikihara, M.Kaburagi, T.Nishino, S.Miyashita and H.-J.Mikeska: "One-Dimensional Heisenberg Anfiferromagnets in which two S=1/2 and two S=1 spins are arranged alternatively" J.Mag.Mag.Matt.(1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] T.Tonegawa, T.Hikihara, M.Kaburagi, T.Nishino, S.Miyashita and H.-J.Mikeska: "Ground-State and Thermodynamic Properties of the Quantum Mixed Spin-1/2-1/2-1-1 Chain" J.Phys.Soc.Jpn.67. (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] S.Watarai and S.Miyashita: "Critical Exponents of Ising-Like Heisenberg Antiferromagnets on the Hexagonal Lattice" J.Phys.Soc.Jpn.67. (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Y.Watanabe,: "New Saturated Ferromagnetism in the Flat-Band Hubbard Model in High Electron Filling" J.Phys.Soc.Jpn.66. 2123-2128 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] S.Miyashita,: "Nature of the Ordered Phase and the Critical Properties of the ThreeDimensional Six-state Clock Model" J.Phys.Soc.Jpn.66. 3411-3420 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] H.De.Raedt,: "Theory of Quantum Tunnening of the Magnetization in Magnetic Particle" Phys.Rev.B. 56. 11761-11768 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] S.Yamamoto,: "Low-Lying Excitations in the S=1 Antiferromagnetic Heisenberg Chain" Phys.Letter A. 235. 545-550 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Y.Watanabe,: "Properties of New Saturated Ferromagnetism in the 1D Flat-Band Hubbard Model as the Spinal State" J.Phys.Soc.Jpn.66. 3981-3987 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] X:Hu,: "Simulation for the First-Order Vortex-Lattice Melting Transition in High-Tc Superconductors" Physica C. 282-287. 2057-2058 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] X:Hu,: "S-function peak in the specificheat of high-Tc Superconductors Monte Carlo simulation" Phys.Rev.Lett.79. 3498-3501 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] S.Miyashita,: "A Stochastic model of non-classical light emission from a micro cavity" Phys.Rev.Lett.80. 1525-1528 (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] T.Tonegawa,: "One-Dimensional Heisenberg Antiferromagnets in which two S=1/2 andtwoS=1 spins are arranged alternatively" J.Mag.Mag.Matt.(1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] T.Tonegawa,: "Ground-State and Thermodynamic Properties of the Quantum Mixed Spin-1/2-1/2-1-1 chain" J.Phys.Soc.Jpn.67. (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] S.Watarai,: "Critical Exponents of Ising-Like Heisenberg Antiferromagnets on the Hexagonal Lattice" J.Phys.Soc.Jpn.67. (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] M.Yamanaka,M.Oshikawa & S.Miyashita: "Hidden Order and Dimerization Transition in S=2 Chain" J.Phys.Soc.Jpn.65・6. 1562-1565 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] M.Roji & S.Miyashita: "On the Extrapolation of the Trotter Number in the Quantum Monte Carlo Simulation of the Magnetization Process" J.Phys.Soc.Jpn.65・7. 1994-1999 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] S.Miyashita: "Observation of the Energy Gap due to the Quantum Tunneling Making Use of the Landau-Zener Mechanism" J.Phys.Soc.Jpn. 65・8. 2734-2735 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] K.Saito,S.Takesue & S.Miyashita: "Thermal conduction in a quantum system" Phys.Rev.E54・3. 2404-2408 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] S.Miyasita and T.Nakamura: "Monte Carlo Studies on Frustrated Quantum Spin Systems by a New Approach to the Negative sign problem" Int.J.Mod Phys.C7・3. 425-431 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] S.Takagi & G.Tatara: "Macroscopic quantum coherence of chirality of a domain wall in ferromagnets" Phys.Rev.B54・14. 9920-9922 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1996-04-01   Modified: 2016-04-21  

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