Summary: Vortex-chain phases in layered superconductors
A. E. Koshelev
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
Received 3 January 2005; published 19 May 2005
Layered superconductors in tilted magnetic field have a very rich spectrum of vortex lattice configurations.
In the presence of in-plane magnetic field, a small c-axis field penetrates in the form of isolated vortex chains.
The structure of a single chain is mainly determined by the ratio of the London and Josephson J lengths,
= / J. At large the chain is composed of tilted vortices tilted chains and at small it consists of a
crossing array of Josephson vortices and pancake stacks crossing chains . We studied the chain structures at
intermediate 's and found two types of behavior. i In the range 0.4 0.5 a c-axis field first penetrates in
the form of pancake-stack chains located on Josephson vortices. Due to attractive coupling between deformed
stacks, their density jumps from zero to a finite value. With further increase of the c-axis field the chain
structure smoothly evolves into modulated tilted vortices and then transforms via a second-order phase tran-
sition into the tilted straight vortices. ii In the range 0.5 0.65 a c-axis field first penetrates in the form
of kinks creating kinked tilted vortices. With increasing the c-axis field this structure is replaced via a first-
order phase transition by the strongly deformed crossing chain. This transition is accompanied by a large jump
of pancake density. Further evolution of the chain structure is similar to the higher anisotropy scenario: it
smoothly transforms back into the tilted straight vortices.
DOI: 10.1103/PhysRevB.71.174507 PACS number s : 74.25.Qt, 74.25.Op, 74.20.De