Flux line in layered superconductors. A single flux line parallel to the layers

The structure of a single flux line is investigated in a field parallel to the layers in superconductors with equivalent and inequivalent layers, using the generalized Lawrence-Doniach model. The magnetic field in a single flux line parallel to the layers extends along the layers over a macroscopic scale when the coupling between the layers is weak. We also derive an expression for the self-energy of a single flux line. The self-energy depends on where the flux line is placed in the layer structure. This dependence causes the intrinsic pinning force for the flux line moving in the direction perpendicular to the layers arising from the layer structure.