Anomalous Metalic State in Strongly Correlated Systems

强相关系统中的反常金属态

• 批准号: 07044078
• 负责人: MAEKAWA Sadamichi
• 金额: $ 4.35万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07044078/
• 关键词: electron correlation; spin charge separation; high Tc superconductivity; Mott transition; anomalous metal; heavy electron; one-dimensional metal; spin fluctuation; gause field; f・電子系; d・電子系; 金属・絶縁体転移; フェルミ流体; 朝永・ラッティンジャー流体

Electronic excitations in low-dimensional strongly correlated systems have attracted considerable attention since the discocvery of high temperature superconductors. In the one-dimensional (1D) systems, it is known that the spin-charge separation occurs and the spin and charge degress of freedom of electrons obey the different dynamics. The elementary excitations of spin and charge are called spinons and holons, respectively. The nature of spin and charge degrees of freedom in the two-dimensional (2D) systems is one of the central issues in the study of high temperature superconductors. Recent advances in angle-resolved photoemission spectroscopy (ARPES) offers an opportunity of testing the theory of the strongly correlated systems.We have studied the single-particle, spin and charge excitations in strongly correlated low-dimensional systems by using the analytical as well as numerical methods. The single-particle spectrum at half-filling is in accord with the recent angle-resolved photoemission spectrum in the 1D cuprate SrCuO_2 and is in strong contrast with that in the 2D one Sr_2CuO_2Cl_2. In 2D,the behaviors of these excitation spectra are strongly dependent on electron concentration. Far away from half-filling, the single-particle spectrum includes both spin and charge excitations as expected in a Fermi liquid. On the other hand, near half-filling, the apectra are rather similar to those in 1D,indicating that the charge and spin degrees of freedom obey the different dynamics.Our study offers a basis of the new quantum theory of solids which starts with the internal degrees of freedom of electrons.

自从高温超导体的发现以来，低维强相关系统中的电子激发引起了人们的广泛关注。在一维系统中，已知存在自旋-电荷分离，电子的自旋自由度和电荷自由度服从不同的动力学。自旋和电荷的基本激发分别称为自旋子和介子。二维系统中自旋和电荷自由度的性质是高温超导体研究的核心问题之一。角分辨光谱学（ARPES）的最新进展为验证强相关体系的理论提供了机会。本文用解析和数值方法研究了强相关低维系统中的单粒子、自旋和电荷激发。半填充时的单粒子光谱与一维cuo_2srcuo_2cl_2的角分辨光谱基本一致，与二维Sr_2CuO_2Cl_2的角分辨光谱形成强烈对比。在二维中，这些激发谱的行为强烈依赖于电子浓度。在费米液体中，单粒子光谱远不是半填充的，它包括自旋和电荷激发。另一方面，在半填充状态下，谱峰与一维中的谱峰非常相似，说明电荷和自旋自由度服从不同的动力学。我们的研究为从电子的内部自由度出发的新的固体量子理论提供了基础。

项目成果

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S.Maekawa: "Frontiers of High Tc Superconductors" North-Holland,Amsterdam, 573 (1996)

S.Maekawa：“高温超导前沿”北荷兰，阿姆斯特丹，573 (1996)