THEORETICAL STUDIES ON MANY-BAND EFFECTS ON SUPERCONDUCTIVITY AND MAGNETISM IN MOLECULAR CRYSTALS

分子晶体超导性和磁性多能带效应的理论研究

• 批准号: 15550010
• 负责人: NAGAO Hidemi
• 金额: $ 1.22万
• 依托单位: KANAZAWA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550010/
• 关键词: superconductivity; many-gap superconductivity; magnetism; crystal structure; many band system; effective electron interactions; electron-phonon interaction; electron pair scattering process; 2重バンド; 有機分子性結晶; 無機結晶; superconductivity; many-gap superconductivity; magnetism; crystal structure; many band system; effective electron interactions; electron-phonon interaction; electron pair scattering process; 2重バンド; 有機分子性結晶; 無機結晶

Many bands play an important role of many gap superconductivity such as MgB_2 superconductor. Form viewpoint of the importance of many-band, we have theoretically investigated new physical properties such as superconducting gaps etc. arising from many-band. Our purposes of this project are (1) to investigate many-band effects on superconductivity, (2) to investigate many-band effects on magnetism and to discuss the possibility of new magnetic properties, and (3) to investigate many-band effects in molecular crystals. In this project, we have investigated many-band effects on superconductivity and magnetism by using Green's function techniques and some many-band models.In many-band effects on superconductivity, we have obtained that the superconducting gap in namy-band systems becomes more stable than that of single band systems. The transition temperature for many-band superconductivity becomes higher than that of single band superconductivity. An effective two-electron pair scattering … More process between bands has a very important role to apper many-band superconductivity. We also have investigated a cooperative mechanism for superconductivity with the pair electron scattering process and the effective electron interactins from electron-phonon interaction. In a single band model such as BCS model, the effective electron interaction should be negative. However, In many-band systems, many-band superconductivity appears, even if the effective electron interaction becomes positive or negative.In many-band effects on magnetism, we have found that effective electron-electron interaction becomes ferromagnetic at half-filling in many-band systems and that antiferromagnetic interaction appears by hole-doping into the many-band systems.We have investigated magnetic and superconducting properties of herringbone and two-layer square lattices in organic crystals. In the two-layer square lattice, we have obtained that we can expect interesting magnetic properties by many-band effects and have also found the possibilities of many-band superconductivity in such two-layer lattices. Less

许多频段在许多差距超导性（例如MGB_2超导体）中起着重要作用。形成了多种频段的重要性的观点，我们从理论上研究了新的物理特性，例如由多频段引起的超导差距等。该项目的目的是（1）研究对超导性的多种频段影响，（2）研究对磁性的多种频段影响并讨论新磁性特性的可能性，以及（3）研究分子晶体中的多波段效应。在这个项目中，我们通过使用Green的功能技术和一些多带模型来研究了对超导性和磁性的多种频段影响。在多波段对超导性的影响中，我们获得了Namy波段系统中的超导间隙变得比单个频段系统更稳定。多波段超导性的过渡温度高于单个带超导的温度。一个有效的两电子对散射…在频段之间进行更多的过程对Apper多波段超导性具有非常重要的作用。我们还研究了一种通过对电子散射过程和电子相互作用的有效电子相互作用的合作机制，用于超导性。在单个频段模型（例如BCS模型）中，有效的电子相互作用应为负。然而，在多种频段系统中，即使有效的电子相互作用变为正或负面。有机晶体中的方格。在两层平方晶格中，我们获得了我们可以期望通过多带效应的有趣磁性特性，并且还发现了这种两层晶格中多带超导性的可能性。较少的