Flux Line Lattice and Defects Interaction in Nanostructured YBa2Cu3O7-d

R. F. LUCCAS; T. PUIG; X. GRANADOS; X. OBRADORS; A. PALAU; A. ROBINSON; A. KURSUMOVIC; J. L. MACMANUS-DRISCOLL; M. G. BLAMIRE

Alicante

Congreso; NES Workshop: Probing superconductivity at the nanoscale; 2008

NES

Analysis of Flux Line Lattice (FLL) interaction with nanoscale defects, especially in nanostructured YBa2Cu3O7-d, is a topic of great importance from a fundamental and a technological point of view, since, only by pinning vortices, the critical current density is enhanced. In this work we present a thoroughly study of the FLL and its interaction with defects (including changes of the FLL symmetry, order and periodicity) by Bitter Magnetic Decoration (BMD). This experimental technique allows the visualization of vortices in large areas (> 1 cm2) with a minimum vortex-to-vortex distance in the sub-micrometre range. Result on superconductor single crystals and films of YBa2Cu3O7-d have been analyzed. We first present an analysis of the FLL order/disorder as a function of the natural defect density and a comparison of single crystal with thin film is shown. Second, artificial nanostructuration of the same samples has been carried out by Focus Ion Beam and Nanoindentation. We will show an analysis by BMD of the competition between natural (pre-existing) and artificial (generated) defects present in the sample, as a function of the order/disorder that each of the different kinds of defects introduce to the FLL. In particular, we confirm that planar defects like twin boundaries strongly break the hexagonal symmetry of FLL and that interfacial artificial defects are able to introduce additional disorder.