Global and local critical current density in superconducting SmFeAsO1−xFx measured by two methods

The critical current densities of polycrystalline bulk SmFeAsO1−xFx prepared by the powder-in-tube (PIT) method and by a conventional solid-state reaction were investigated using the remnant magnetic moment method and Campbell’s method. Two types of shielding current, corresponding to global and local critical current densities Jc were observed using both measurement methods. The global and local Jc were on the order of 107 A/m2 and 1010 A/m2 at 5 K, respectively. The local Jc decreased slightly with increasing magnetic field. The global Jc was independent of the preparation method, while the local Jc was larger for samples prepared by PIT than for those prepared by solid-state reaction.