We propose a new Ginzburg-Landau model for intrinsic layered superconductors. In this model the spatial dependent coefficients in the Ginzburg-Landau free energy are assumed to describe the layer structure. This model mediates between the homogeneous anisotropic effective mass model and the Lawrence-Doniach model. Solving the GL equations numerically, we calculated, we calculate the upper critical fields parallel and perpendicular to the layers, Hc21 and Hc2∥. The temperature dependence of Hc21 shows the crossover behavior from 3D to 2D as temperature decreases. We also calculate the lower critical fields parallel and perpendicular to the layers in the high-k limit. In superconductors with strong layer nature the flux line state parallel to the layers may be unstable at high temperatures near Tc.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering