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

使用它，我们估计了几种材料的差距放大器。超氟 ^3He和纺纱碱基因恒温器的vortex结构在过渡温度附近的金茨堡 - 兰德方程式上浓缩，我们对快速旋转的超级富裕 ^3He的涡旋结构进行了理论研究，以呈现整个阶段的涡旋结构。我们还预测了三组分旋转玻璃棒凝结物的新型涡旋结构。Maki参数的计算Maki参数是II型超导体中最基本的参数之一，它与特定的水上跳跃相关，与特定的旋转相关，在过渡时期的变化，在跨度上进行了更强的依赖性的依赖性等等。详细的费米 - 表面结构，尤其是在院长材料中。II型超导体的上部临界场的计算上临界场H_ <c2>是II型超导体中最基本的数量之一。很长一段时间以来，H_ <c2>干净的样品取决于详细的费米 - 表面结构。但是，尚未进行详细的计算。我们得出了一个H_ <c2>方程式，该方程使我们能够通过使用第一原理电子结构计算的费米表面进行定量计算H_ <c2>。使用它，我们对NB，NBSE_2和MGB_2的H_ <c2>进行了详细研究，以找到与实验的出色定量协议。对H_ <c2>附近I型II超导体的通量抵抗力的计算，在H_ <c2>附近的II III超级范围的电子电阻均具有相同的范围，这是一种相似的范围，该活动是相同的范围。适当地。我们对临界场附近的磁通电阻进行了详细的计算，以阐明总体温度和杂质浓度依赖性。较少的