| Project/Area Number |
15540358
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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 |
Mathematical physics/Fundamental condensed matter physics
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| Research Institution | Shibaura Institute of Technology (2004-2005)
Tohoku University (2003) |
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Principal Investigator |
NAKAMURA Tota Shibaura Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (50280871)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | spin glasses / nonequilibrium relaxation method / slow dynamics / chirality / dynamic universality / 動的臨界指数 / カイラルグラス / スピングラス相関長 / 液滴描像 / カイラリティ機構 / 並列計算機 |
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| Research Abstract |
The aim of this research project is to clarify the spin-glass (SG) transition in the Heisenberg spin-glass model in three dimensions. In order to achieve thorough understandings of the SG transition and the low-temperature phase, we also investigated the XY model and the Ising model. Our main results are as follows.
1.Development of efficient numerical recipes : We developed various protocols of the finite-time scaling analysis in order to improve the accuracy.
2.Resolution of the spin- and the chiral-glass transitions in the Heisenberg SG model in three dimensions : The chiral-glass transition is confirmed to occur at higher temperature than the spin-glass transition temperature. We also observed that the spin and the chirality are decoupled above the SG transition temperature and become coupled below it.
3.Dynamic universality : We found a possibility of the dynamic universality in the spin- and the chiral-glass transitions in three dimensions. All the investigated phase transition exhibit the same dynamic critical exponent.
4.Low-temperature crossover in the SG phase : We found a crossover temperature in the spin-glass phase, where the ground-state relaxation appears. The dynamic behavior below this crossover temperature is equivalent to the T=0 dynamics. A dynamic exponent of the ground state is also estimated. It takes almost the same value between the Ising model and the Heisenberg model.
5.Preparation for the quantum spin-glass problems : We investigated the quantum phase transition of the random alternating quantum spin chain. Our developed method is confirmed to be applicable to this interesting problems.
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