Dynamic studies of vortices in NbSe2, from single flux lines to lattices

We present different techniques to study the dynamics of the vortex lattice in NbSe2 single crystal samples. In the first set of experiments, we applied a field parallel to the c crystalline axis and extended the Bitter decoration technique to the study of dynamic structures by imaging the lattice during creep ({''}decoration during motion{''}). This method exposed a new smectic phase and an anisotropic ``crystal{''} at higher fields. In the second set, we used a micro-mechanical high-e oscillator to study the mesoscopic flux dynamics along the crystallographic ab plane. In this case, we were able to observe single vortex penetration, well described by a `1 + 1' -dimensional model. (C) 2000 Published by Elsevier Science B.V. All rights reserved.