Josephson vortices and solitons inside pancake vortex lattice in layered superconductors

 

 

 

In very anisotropic layered superconductors tilted magnetic field generates two interpenetrating vortex sublattices. This set of crossing lattices contains a sublattice of Josephson vortices and a sublattice of pancake-vortex stacks. The pancake-vortex sublattice modifies structure of the Josephson vortex in a very unusual way.  Josephson vortex induces deformations in the pancake vortex crystal, which, in turn, substantially modify the Josephson vortex structure. The phase field of the Josephson vortex is composed of two types of phase deformations: the regular phase and vortex phase. The phase deformations with smaller stiffness dominate. The contribution from the vortex phase smoothly takes over with increasing magnetic field. The core structure depends on the ratio of the London penetration depth l and the bare size of Josephson vortex core l_J and experiences a smooth yet qualitative evolution with increase of this ratio. At small ratios l/l_J pancakes have only small deformations with respect to position of the ideal crystal (see upper structure in the Figure), while at higher ratios the pancake stacks in the central row smoothly transfer between the neighboring lattice positions forming a solitonlike structure (see lower structure in the Figure).

Figure: Structure of the in-plane vortex inside the pancake lattice for two values of the ratio l/l_J. Left column shows graylevel plot of the cosine of the interlayer phase difference and right column shows pancake coordinates in the central row.