The puzzle of 90 degree reorientation in the vortex lattice of   borocarbide superconductors
  We explain 90 degree reorientation in the vortex lattice of borocarbide superconductors on the basis of a phenomenological extension of the nonlocal London model that takes full account of the symmetry of the system. We propose microscopic mechanisms that could generate the correction terms and point out the important role of the superconducting gap anisotropy. 
Anton Knigavko and Baruch Rosenstein