Theoretical Investigations on the spin-glass phase transitions and its low-temperature phase using the nonequilibrium relaxation method
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
Mathematical physics/Fundamental condensed matter physics
|Research Institution||Shibaura Institute of Technology(2004-2005)|
NAKAMURA Tota Shibaura Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (50280871)
|Project Period (FY)
2003 – 2005
Completed(Fiscal Year 2005)
|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)
|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|
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.
Research Products (10results)