Large critical current density in neutron-irradiated polycrystalline HgBa2CuO4+ delta

Enhanced flux pinning in Ag-sheathed Bi(Pb)–Sr–Ca–Cu–O superconductors tapes with addition of magnetic nanorod γ-Fe2O3

The pinning strength of the Ag-sheathed Bi(Pb)–Sr–Ca–Cu–O tapes with the addition of magnetic nanorod γ-Fe2O3 is studied using the exponent n values obtained from power law current-electric field (I-E) characteristics. The starting composition of the γ-Fe2O3 added samples is Bi1.6Pb0.4Sr2Ca2Cu3O10-(γ-Fe2O3)0.01. The rate of decrease of n values in applied fields for the tapes with nano-γ-Fe2O3 is found lower than the tapes without nano-γ-Fe2O3. This indicates that the pinning strength for the tapes with nano γ-Fe2O3 is relatively higher than the tapes prepared without nano γ-Fe2O3. The results are supported by two conventional methods which are normally used to compare the pinning strength of superconductor tapes. Magnetic impurities generally suppress superconductivity. However, our study shows that magnetic nanorod γ-Fe2O3 enhanced the pinning strength of Ag-sheathed Bi–Sr–Ca–Cu–O superconductor tapes. This is consistent with previous calculations on frozen flux superconductor with magnetic nanorod as pinning centers.