Semi-Meissner state and non-pairwise intervortex interactions in   type-1.5 superconductors
  We demonstrate existence of non-pairwise interaction forces between vortices in multicomponent and layered superconducting systems. That is, in contrast to most common models, the interactions in a group of such vortices is not a universal superposition of Coulomb or Yukawa forces. Next we consider the properties of vortex clusters in Semi-Meissner state of type-1.5 two-component superconductors. We show that under certain condition non-pairwise forces can contribute to formation of very complex vortex states in type-1.5 regimes. 
Johan Carlstrom, Julien Garaud, Egor Babaev
cond-mat.supr-con