分子性導体での異方的超伝導と量子相転移の最適化変分モンテカルロ法による研究

分子导体中各向异性超导性和量子相变的优化变分蒙特卡罗研究

• 批准号: 18028005
• 负责人: 横山 寿敏
• 金额: $ 1.15万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-18028005/
• 关键词: モット転移; ダブロン-ホロン相関; 反強磁性; d波; ハバードモデル; κ-ET塩; 三角格子; 変分モンテカルロ法; ダブロンーホロン相関

分子性結晶物質のκ-ET塩は、狭バンドで相対的に電子相関が強く、反強磁性秩序、モット転移、異方的超伝導といった強相関系で起こる様々な現象が見られる。この物質は異方的三角格子上の単バンドハーフフィリングのハバード模型で、電子的性質がうまく記述できると考えられ、置換基や圧力を変えることで、異方性パラメーターt'やバンド幅(相関強度)U/tを変えられる。最近、等方性のよい化合物で非磁性の超伝導・絶縁体転移が見出されて話題になっている。本研究では上記モデルに対し、あらゆる相関強度で局所相関効果を厳密に扱うことが可能な変分モンテカルロ法を用いて、基底状態の様々な性質を議論し、このモデルとET塩の物理を総合的に考える。初年度ほ、d波一重項状態の性質を中心に考えた。変分試行関数としてd波対称性のBCS関数に同一サイト相関因子とダブロン-ホロン間の束縛因子を取り入れて計算を行った。後者を導入することにより、非磁性状態で定性的に正しいモット転移の記述ができた。一方、反強磁性は独立な波動関数を用いて考えた。これらの成果を基に、2年目はd波一重項と反強磁性長距離秩序を同時に取り込み、さらに相互作用によるバンドくり込みの効果を直接扱える波動関数と、等方的パラメーター領域で優位性が高い120度スピン構造をもった反強磁性状態の計算をそれぞれ行った。その結果、大きなU/t(>8)のときt'/tがかなり大きな値(〜0.9)まで、通常の反強磁性秩序相が占め、等方点(t'/t=1)近傍からt'/tが1.6程度までは120度反強磁性状態が安定化することが判った。一軸的対称性を好む時間反転対称性の破れたd+d波やd+id波の一重項状態は、さらに対角方向にホッピングが強い場合に現れることが判った。

The molecular structure, the κ-ET phase, the phase strength of the narrow phase, the reverse magnetic order, the phase shift of the superconductor, and the strong phase of the superconducting phase are similar to those of the phase transition. On the triangle grid of the property market, we need to know that the model is correct, the computer's performance record is correct, the basic force is sensitive, and the amplitude (relative strength) of the computer is very strong. Recently, the non-magnetic superconductor of the isobaric compound has been moved to cause a large number of problems. In this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the results of this study are as follows: in this study, the At the beginning of the year, there is an important project of "d wave" and "d wave" in the center of the center. The number of rows, the number of waves, the symmetry, the BCS, the same correlation factor, the correlation factor, the cluster factor, the correlation factor, the correlation factor In the latter part, the data is recorded in the non-magnetic qualitative system. One side, the anti-strong magnetic field independent wave movement number is tested. On the basis of the results of the experiment, the two-year-long-term anti-magnetic long-distance separation system is used at the same time, and the interaction effect is used to directly determine the number of wave movements. in the field of the same party, the high altitude of 120 degrees in the field is used to calculate the magnetic properties of magnetic states. The results show that the magnetic stability of the magnetic state is much stronger than that of the normal magnetic field (& gt;8). The results show that the magnetic stability of the magnetic state is much stronger than that of the magnetic stability of the magnetic state. The results show that the magnetic stability of the magnetic state is slightly stronger than that of the magnetic state. Once the symmetry is good, the time is anti-symmetry, the symmetry is broken, the wave of the d+id wave is one of the items, and the angle direction of the cable is in the right direction.

项目成果

Superconductivity and a Mott transition in a Hubbard model on an anisotropic triangular lattice model.

各向异性三角晶格模型上哈伯德模型中的超导性和莫特转变。

• 发表时间: 2006
• 期刊: Journal of Physcal Society of Japan 75
• 作者: T. Watanbe;et. al.;K. Kobayashi and H. Yokoyama;T.Watanabe et al.;T.Watanabe et al.
• 通讯作者: T.Watanabe et al.

Mott Transitions and Superconductivity in Half-Filled-Band Hubbard Model on Square Lattice wi th Geometric Frustration

几何挫败方晶格半满带哈伯德模型中的莫特跃迁和超导性

• 发表时间: 2006
• 期刊: J. Phys. Soc. Jpn. 75
• 作者: H.Yokoyama;et al.
• 通讯作者: et al.

フェルミ系とボース系のモット転移機構

费米和玻色系统的莫特跃迁机制

• 发表时间: 2007
• 作者: R. Yoshii;M. Eto;横山寿敏
• 通讯作者: 横山寿敏

Variational Monte Carlo study of pairing symmetry in Sr2RuO4

Sr2RuO4 配对对称性的变分蒙特卡罗研究

• 发表时间: 2007
• 期刊: Physica C 463-465(134-137)
• 作者: S.Fujita;T.Watanabe;S.Onari;H.Yokoyama;Y.Tanaka;J.Inoue
• 通讯作者: J.Inoue

2次元ボースハバード模型の性質

2D Bose-Hubbard 模型的属性

• 发表时间: 2008
• 作者: 横山寿敏;小形正男
• 通讯作者: 小形正男