Plastic and elastic symmetry transformations induced in the vortex lattice of anisotropic and layered superconductors

We make a comparative analysis of the response of the three-dimensional vortex lattice in Bi-2 Sr-2 CaCu2O8 and NbSe2 to the presence of square arrays of pinning sites localized at one extremity of the vortex crystals. The absence of the hexagonal to square symmetry transformation and the induction of a distorted hexagonal symmetry in the vortex lattice of NbSe2 contrast to the observed symmetry change in Bi2Sr2CaCu2O8. The dissimilar response in both cases is explained taking into account the vortex structure solidification mechanisms in both materials: The plastic response in the case of the layered material Bi2Sr2CaCu2O8 is suggested to be a result of the simultaneity of solidification and coupling of bidimensional pancake vortices whereas a viscous solidification is the responsible for the three-dimensional elastic response in NbSe2.