Critical current densities of Sr0.6K0.4Fe2As2 superconductors estimated from AC susceptibilities

AC susceptibilities (real χ ′ and imaginary χ ″) of Sr 0.6 K 0.4 Fe 2 As 2 (122 type) polycrystalline with Ag addition are analysed by the grained Bean model. A variety of characteristics, double peak in χ ″ and shoulder transition in χ ′, appear in the model simulation. Comparing the measured χ ′ and χ ″ with the model allows more clear insight on the polycrystalline structure. Estimated critical current densities J cg and J cl of the grain and the link in the iron-based pnictides show that the addition of 20 wt.% Ag increases J cl 9 times larger. Improvement of intergrain characteristics with Ag addition is clearly indicated.