Study of two-dimensional strongly correlated systems on the basis of Quantum Monte Carlo simulations and first principles calculations

基于量子蒙特卡罗模拟和第一性原理计算的二维强相关系统研究

基本信息

批准号：
19540388
负责人：
YANAGISAWA Takashi
金额：
$ 2.08万
依托单位：
National Institute of Advanced Industrial Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2007
资助国家：
日本
起止时间：
2007 至 2009
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-19540388/
关键词：
強相関電子系計算物理強相関雷子系

项目摘要

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.

我们对 Hubbard 模型和三带 d-p 模型进行了量子和变分蒙特卡洛模拟，以阐明高温超导体的物理性质。利用 Gutzwiller ansatz 对二维 d-p 模型进行的数值研究表明，不可通约的反铁磁。状态与超导共存于低掺杂和轻掺杂区域，该相图与最近的层状高温实验一致。我们还对具有 Bi-2212 型能带的二维 t-t'-t"-U Hubbard 模型进行了变分蒙特卡罗模拟，以检查最近观察到的 4×4 棋盘态的稳定性。通过Bi-2212中的扫描隧道显微镜，我们发现以多Q集为特征的以键为中心的四周期对角和垂直自旋棋盘结构的共存状态是稳定的。我们提出了一种基于量子蒙特卡罗方法和精确对角化方法来评估自旋磁化率和对磁化率等磁化率的方法，并利用量子蒙特卡罗方法检查了磁化率。半填充时的自旋磁化率和对磁化率分别与排斥和吸引相互作用的 d 波和 s 波对称性的相关性我们已经表明，结果是一致的。随着科斯特利茨-托利斯转变的存在。