Shrinking Magnetic Vortices in V3Si Due to Delocalized Quasiparticle   Core States: Confirmation of the Microscopic Theory for Interacting Vortices
  We report muon spin rotation measurements on the conventional type-II superconductor V3Si that provide clear evidence for changes to the inner structure of a vortex due to the delocalization of bound quasiparticle core states. The experimental findings described here confirm a key prediction of recent microscopic theories describing interacting vortices. The effects of vortex-vortex interactions on the magnetic and electronic structure of the vortex state are of crucial importance to the interpretation of experiments on both conventional and exotic superconductors in an applied magnetic field. 
J. E. Sonier, F. D. Callaghan, R. I. Miller, E. Boaknin, L. Taillefer,   R. F. Kiefl, J. H. Brewer, K. F. Poon, J. D. Brewer