Theoretical study on vortex states in superconductors

超导体涡旋态的理论研究

基本信息

批准号：
13640341
负责人：
KITA Takafumi
金额：
$ 1.86万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

Theory of the de Haas-van Alphen effect in type-II superconductorsWe performed numerical and analytical studies of the de Haas-van Alphen oscillation in type-II superconductors. We derived an analytic formula for the extra attenuation observed in the vortex state, which can also be used to estimate the band and/or angle dependent gap anisotropy. Using it, we estimated gap amplitude of several materials.Vortex structures of superfluid ^3He and spinor Base-Einstein condensatesBased on the Ginzburg-Landau equations near the transition temperature, we performed a theoretical study on the vortex-lattice structures of superfluid ^3He in rapid rotation to present an entire phase diagram. We also predicted novel vortex structures of the three-component spinor Bose-Einstein condensate.Calculation of the Maki parameterThe Maki parameter is one of the most basic quantities in type-II superconductors which is relevant to the specific-heat jump at the transition, the change in the slope of the magn … More etization curve at the transition, etc. We performed a detailed study on it to show that it has a strong dependent on the detailed Fermi-surface structures, especially in dean materials.Calculation of the upper critical field of type-II superconductorsThe upper critical field H_<c2> is one of the most basic quantities in type-II superconductors. It has been knownn for a long time that H_<c2> of clean samples depends on the detailed Fermi-surface structures. However, few detailed calculations have been performed yet. We derived an H_<c2> equation which enables us to calculate H_<c2> quantitatively by using Fermi surfaces from first-principles electronic-structure calculations. Using it, we performed detailed studies on H_<c2> of Nb, NbSe_2, and MgB_2 to find excellent quantitative agreements with experiments.Calculation of the flux-flow resistivity of type-II superconductors near H_<c2>The electronic resistance in the vortex state of type-II superconductors is a complicated phenomenon involving the motion of vortices which has not been understood sufficiently. We performed a detailed calculation on this flux-flow resistivity near the upper critical field to clarify the overall temperature and impurity-concentration dependences. Less

II型超导体中的德哈斯-范阿尔芬效应理论我们对II型超导体中的德哈斯-范阿尔芬振荡进行了数值和分析研究，我们推导出了在涡旋状态下观察到的额外衰减的解析公式。也可用于估计能带和/或角度相关的间隙各向异性，使用它，我们估计了几种材料的间隙幅度。超流体 ^3He 和旋量的涡流结构。基础爱因斯坦凝聚基于转变温度附近的Ginzburg-Landau方程，我们对快速旋转的超流体^3He的涡旋晶格结构进行了理论研究，以呈现出完整的相图，我们还预测了三元的新颖涡旋结构。 Maki参数的计算Maki参数是II型超导体中最基本的量之一，它是与转变时的比热跳跃、转变时磁化曲线斜率的变化等有关。我们对其进行了详细的研究，表明它对详细的费米面有很强的依赖性II型超导体上临界场的计算上临界场H_<c2>是II型超导体中最基本的物理量之一。干净样品的 H_<c2> 取决于详细的费米表面结构，但是，我们还没有进行过详细的计算。 -电子结构计算原理，我们对 Nb、NbSe_2 和 MgB_2 的 H_<c2> 进行了详细研究，以找到与实验良好的定量一致性。通量流的计算H_<c2>附近II型超导体的电阻率 II型超导体涡旋状态下的电子电阻是一种复杂的涡旋运动现象，我们对这种附近的磁通流电阻率进行了详细的计算。上临界场以澄清总体温度和杂质浓度依赖性。