第二类超导体的下临界磁场的新计算(英文)

A novel calculation of the lower critical field of typeⅡsuperconductor

从Ginzburg-Landau理论出发,对理想第二类超导体的下临界磁场做计算.通过比较两相的吉布斯自由能,特别是考虑相变时的熵增,最终求得下临界场的新公式,得到纯超导体的下临界场对温度的依赖与经验公式有所不同.作者把这种不同归结为超导体的G—L参数对温度的依赖.

The lower critical magnetic field of ideal type II superconductors is calculated in a way different from Ginzburg-Landau theory. By comparing the Gibbs free energy difference of the two phases, especially with entropy increase being taken into account, the lower critical magnetic field is obtained. In pure superconductors the calculated temperature dependence of lower critical field shows a negative curvature which is different from the empirical formula. We attribute this difference to the fact that real superconductors have a temperature-dependent G-L parameter k（T）.