Time Resolved Stroboscopic Neutron Scattering of Vortex Lattice Dynamics   in Superconducting Niobium
  Superconducting vortex lattices, glasses and liquids attract great interest as model systems of crystallization and as a source of microscopic information of the nature of superconductivity. We report for the first time direct microscopic measurements of the vortex lattice tilt modulus c44 in ultra-pure niobium using time-resolved small angle neutron scattering. Besides a general trend to faster vortex lattice dynamics for increasing temperatures we observe a dramatic changeover of the relaxation process associated with the non-trivial vortex lattice morphology in the intermediate mixed state. This changeover is attributed to a Landau-branching of the Shubnikov domains at the surface of the sample. Our study represents a showcase for how to access directly vortex lattice melting and the formation of vortex matter states for other systems. 
S. M\"uhlbauer, C. Pfleiderer, P. B\"oni, E. M. Forgan, E. H. Brandt,   A. Wiedenmann, U. Keiderling, G. Behr
cond-mat.str-el cond-mat.supr-con