| Project/Area Number |
19540388
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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 |
Condensed matter physics II
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| Research Institution | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
YANAGISAWA Takashi National Institute of Advanced Industrial Science and Technology, エレクトロニクス研究部門, 研究グループ長 (90344217)
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| Co-Investigator(Kenkyū-buntansha) |
HASE Izumi 独立行政法人産業技術総合研究所, エレクトロニクス研究部門, 主任研究員 (00357774)
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| Project Period (FY) |
2007 – 2009
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| Project Status |
Completed (Fiscal Year 2009)
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| Budget Amount *help |
¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2009: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2008: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 強相関電子系 / 計算物理 / 強相関雷子系 |
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| Research Abstract |
We have carried out quantum and variational Monte Carlo simulations for the Hubbard model and three-band d-p model to clarify the physics of high-temperature superconductors. Numerical studies of the two-dimensional d-p model by using the Gutzwiller ansatz have exhibited that the incommensurate antiferromagnetic state coexists with superconductivity in the under- and lightly doped regions. The phase diagram is consistent with recent experiments for layered high- temperature cuprates. We have also performed a variational Monte Carlo simulation on the two-dimensional t-t'-t"-U Hubbard model with Bi-2212-type band to examine the stability of a 4×4 checkerboard state which has been observed recently by scanning tunneling microscopy in Bi-2212. We have found that the coexistent state of bond-centered four-period diagonal and vertical spin-checkerboard structure characterized by a multi-Q set is stabilized and composed of 4×4 period checkerboard spin modulation. We have proposed a method to evaluate susceptibilities such as the spin susceptibility and pair susceptibility on the basis of quantum Monte Carlo methods and exact diagonalization method. Using quantum Monte Carlo method, we have examined the size dependence of the spin susceptibility at half filling and pair susceptibilities with d- and s-wave symmetries for the repulsive and attractive interactions, respectively. We have shown that the results are consistent with the existence of the Kosterlitz-Thouless transition.
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