Flux pinning in PrFeAsO and NdFeAsOF superconducting crystals

Van der Beek, C. J.*; Rizza, G.*; Konczykowski, M.*; Fertey, P.*; Monnet, I.*; Klein, T.*; Okazaki, Ryuji*; Ishikado, Motoyuki; Kito, Hijiri*; Iyo, Akira*; et al.

Physical Review B, 81(17), p.174517_1 - 174517_11, 2010/05

https://doi.org/10.1103/PhysRevB.81.174517

Local magnetic measurements are used to quantitatively characterize heterogeneity and flux line pinning in PrFeAsO and NdFeAs(O,F)superconducting single crystals. In spite of spatial fluctuations of the critical current density on the macroscopic scale, it is shown that the major contribution comes from collective pinning of vortex lines by microscopic defects by the mean-free path fluctuation mechanism. The defect density extracted from experiment corresponds to the dopant atom density, which means that dopant atoms play an important role both in vortex pinning and in quasi-particle scattering.