Global and local critical current density in superconducting SmFeAsO${}_{1-x}$F${}_x$ measured by two methods

Abstract

The critical current densities of polycrystalline bulk SmFeAsO${}_{1-x}$F${}_x$ 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 $J_{\mathrm{c}}$ were observed using both measurement methods. The global and local $J_{\mathrm{c}}$ were on the order of $10^7$ A/m${}^2$ and $10^{10}$ A/m${}^2$ at 5 K, respectively. The local $J_{\mathrm{c}}$ decreased slightly with increasing magnetic field. The global $J_{\mathrm{c}}$ was independent of the preparation method, while the local $J_{\mathrm{c}}$ was larger for samples prepared by PIT than for those prepared by solid-state reaction.

20 pages, 5 figures. to be published in Physica C