Theory on vortex states in anisotropic superconductors with strong correlation

强相关各向异性超导体涡旋态理论

• 批准号: 10640334
• 负责人: OGATA Masao
• 金额: $ 2.11万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640334/
• 关键词: strong correlation; vortex in anisotropic super conductors; t-J model; high-Tc superconductivity

We studied theoretically ab014t the anomalous behaviors of the electronic states near the vortex cores as well as the relating phenomena, using the two-dimensional t-J model in which the anisotropic superconductivity with strong correlation is realized. For this purpose we developed the programs for numerical calculations and applied them to various cases. The obtained results are summarized as follows :1. We studied the electronic states near the vortex core of high-TィイD2cィエD2 superconductors by applying the Gutzwiller approximation to the Bogoliubov-de Gennes equations. As a result, we found possibilities that an extended s-wave component and antiferromagnetic correlations are induced inside the core when the doping rate is small.2. We examined the ground state of the two-dimensional t-J model using the variational Monte Carlo simulation which was extended for the case with antiferromagnetic order parameters. It was found that the d-wave superconductivity and antiferromagnetism coexist near half filling.3. We extended the Gutzwiller approximation for studying the strong correlation, by comparing the numerical results and analytical methods. The obtained extended approximation can be easily applied to the Bogoliubov-de Gennes equations. We used this method for the cases with antiferromagnetic correlations.4. We studied the electronic states near the boundary and impurities in the t-J model, which are closely related to the vortex problem. Some new features were found about the dependence of the surface states on the shape of the Fermi surface and about the magnetic impurities.5. We investigated the stripe state in which the antiferromagnetism and d-wave superconductivity coexist using the extended Gutzwiller approximation. It was found that some impurity pinning potential is necessary to stabilize the stripe states.

本文利用实现强关联各向异性超导的二维t-J模型，从理论上研究了涡旋核附近电子态的反常行为及相关现象。为此，我们开发了数值计算程序，并将其应用于各种情况。主要研究结果如下：1.采用Gutzwiller近似对Bogoliubov-de Gennes方程组进行近似，研究了高温超导体D_2c超导体D_2c超导体涡旋核附近的电子态.结果发现，当掺杂率较小时，在芯内可能会产生扩展的s波分量和反铁磁关联.我们用变分Monte Carlo方法研究了二维t-J模型的基态，并将其推广到反铁磁序参量的情形。发现在半填充附近d波超导和反铁磁性共存.通过数值计算结果与解析方法的比较，我们推广了Gutzwiller近似来研究强关联。所得到的扩展近似可以很容易地应用于Bogoliubov-de Gennes方程。我们将这种方法用于反铁磁关联的情况.我们研究了t-J模型中与涡旋问题密切相关的边界附近的电子态和杂质。发现了表面态对费米面形状的依赖关系以及磁性杂质的一些新的特征.在推广的Gutzwiller近似下，研究了反铁磁性和d波超导共存的条纹态。结果表明，一定的杂质钉扎势是稳定条纹态所必需的。

项目成果

H. Tsuchiura: "Quasiparticle properties around a nonmagnetic impurity in the superconducting state of the two-dimensional t-J model"J. Phys. Soc. Jpn. 68. 2510-2513 (1999)

H. Tsuchiura：“二维 t-J 模型超导态非磁性杂质周围的准粒子特性”J。

H. Tsuchiura, Y. Tanaka, M. Ogata and S. Kashiwaya: "Local density of states around a magnetic impurity in high-TィイD2cィエD2 Superconductors based on the t-J model"Phys. Rev. Lett.. (to appear).

H. Tsuchiura、Y. Tanaka、M. Ogata 和 S. Kashiwaya：“基于 t-J 模型的高 T2CieD2 超导体中磁性杂质周围的局域密度”Phys Rev. Lett..（待发表）。

Y. Tanuma, Y. Tanaka, M. Ogata and S. Kashiwaya: "Quasiparticle states near surfaces of high-TィイD2cィエD2 Superconductors based on the extended t-J model"Phys. Rev. B. vol. 60. 9817-9826 (1999)

Y. Tanuma、Y. Tanaka、M. Ogata 和 S. Kashiwaya：“基于扩展 t-J 模型的高 T2CieD2 超导体表面附近的准粒子态”Phys Rev. B. vol. 60. 9817 -9826 (1999)

A.Himeda: "Coexistence of dx^2-y^2 superconductivity and antiferromagnetism in the two-dimensional t-J model and numerical estimation of Giutzwiller factors"Phys.Rev.B. 60. 9935-9938 (1999)

A.Himeda：“二维 t-J 模型中 dx^2-y^2 超导性和反铁磁性的共存以及 Giutzwiller 因子的数值估计”Phys.Rev.B。

M. Ogata: "Electronic States and Mixing of Different Symmetry or Antiferromagnetism in Vortex Cores in dィイD2xィエD2ィイD12ィエD1ィイD2-yィエD2ィイD12ィエD1-wave Superconductivity"Int. J. Mod. Phys. B.. (to appear).

M. Ogata：“D1 波超导中涡核中不同对称性或反铁磁性的混合”Int Phys B..（即将出版）。