Muon spin rotation measurements of the vortex state in vanadium: A   comparative analysis using iterative and analytical solutions of the   Ginzburg-Landau equations
  We report muon spin rotation measurements on a single crystal of the marginal type-II superconductor V. The measured internal magnetic field distributions are modeled assuming solutions of the Ginzburg-Landau (GL) equations for an ideal vortex lattice obtained using (i) an iterative procedure developed by E.H. Brandt, Phys. Rev. Lett. 78, 2208 (1997) and (ii) a variational method. Both models yield qualitatively similar results. The magnetic penetration depth (lambda) and the GL coherence length (xi) determined from the data analysis exhibit strong field dependences, which are attributed to changes in the electronic structure of the vortex lattice. The zero-field extrapolated values of lambda and the GL parameter kappa agree well with values obtained by other experimental techniques that probe the Meissner state. 
M. Laulajainen, F.D. Callaghan, C.V. Kaiser, and J.E. Sonier