Original scientific paper
Vortex pinning and critical currents in nanostructured novel superconductors
Ivica Kušević
; Department of Physics, Faculty of Science, University of Zagreb, HR-10000 Zagreb, Croatia
Emil Babić
; Department of Physics, Faculty of Science, University of Zagreb, HR-10000 Zagreb, Croatia
Abstract
A systematic analysis of the parameters associated with vortex pinning in novel superconductors containing nano-scale strong isotropic pinning centres (such as U/n processed Bi2223/Ag tapes and nanoparticle added MgB2) has been carried out. Although the systems studied are very different as regards their structures, types of nano-scale defects and vortices, their pinning parameters (irreversibility fields and the fields for the maximum volume pinning force) show distinct common features. In particular, for moderate defect densities nφ, in all these systems the enhancement of the pinning parameters in nanostructured state is approximately linear in nφ over sizable field and temperature windows. Accordingly, these systems exhibit a kind of matching effects with the effective matching field Bφ, correlated with the areal density of defects. The field Bφ forms a natural field scale for the vortex pinning phenomena in such systems. However, at fields far from Bφ, an interplay of different pinning mechanisms sets in. The impact of these results for the future enhancement of the flux pinning and critical currents in nanostructured Bi2223 and MgB2 superconductors is briefly discussed.
Keywords
novel superconductors; vortex pinning; U/n processed Bi2223/Ag; MgB2
Hrčak ID:
301945
URI
Publication date:
1.3.2005.
Visits: 159 *