Quantum Monte Carlo Study of Novel Phases and Phases Transitions
| Project/Area Number |
14540361
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物性一般(含基礎論)
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| Research Institution | The University of Tokyo (2004)
Tokyo Metropolitan University (2002-2003) |
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Principal Investigator |
KAWASHIMA Naoki The University of Tokyo, The Institute for Solid State Physics, associate professor, 物性研究所, 助教授 (30242093)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2004: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2002: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Quantum Critical Phenomena / Quantum Monte Carlo / Field-Induced Ordering / SU(4) symmetry / Quantum Spin Systems / Statistical Mechanics / SU / 対称性 / モンテカルロ法 / スピングラス / ランダムネス / 臨界現象 / 計算物理学 |
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| Research Abstract |
The development of the numerical methods and computers in recent years has made the numerical calculations in physics significantly more important. In particular, it is now possible to study various lattice models very efficiently by the quantum Monte Carlo method. As a result, several unsolved problems have come within the reach of numerical investigations. In the present project we aimed at (1) the further development of numerical methods for widen the class of solvable models and (2) clarifications of physical properties of various relevant models that are made tractable by the new methods. To be concrete, we have investigated disordered states with some spatial structure and the quantum critical phenomena induced by a strong external magnetic field. For the development of the new methods, we considered the world-line method, which samples the various configurations in the path-integral formulation. Of a particular importance was the extension of the worm updating to the cases with large spins. We also considered SU(N) model that had been regarded as a candidate for disordered (spin-liquid) ground state. We also proposed a new method for bosonic problems as well. As for the SU(N) model, we performed a simulation in the case of N=4 and demonstrated that the spin liquid ground state proposed in the previous studies does not exist. Instead the true ground state turned out to be a Neel state. As for the field induced magnetic ordering, we observed that the quantum criticality is characterized by the mean-field type scaling, in spite of a number of experimental results. The disagreement may be attributed to the relatively high temperatures where the most experiments had been carried out. We also presented an analytic argument that supports these numerical results.
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Report
(4 results)
Research Products
(27 results)
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[Journal Article] Magnetic-field-induced condensation of triplons in Han purple pigment BaCuSi2O62004
Author(s)
M.Jaime, V F.Correa, N.Harrison, C.D.Batista, N.Kawashima, Y.Kazuma, G.A.Jorge, R.Stern, I.Heinmaa, S.A.Zvyagin, Y.Sasago, K.Uchinokura
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Journal Title
Physical.Review Letters vol.93
Pages: 87203-87206
Description
「研究成果報告書概要(欧文)」より
Related Report
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