Analysis of the critical current density and flux pinning properties in iron-based Ba0.55K0.45Fe2As2 high-Tc superconductor

The critical current density and flux pinning properties of the Ba0.55K0.45Fe2As2 high-Tc superconductor with Tc = 37 K are studied using the field and the time dependences of the magnetization. The temperature dependence of the critical current density Jc(T) has been found to follow the form Jc ∝ (1−T/Tc)n and is consistent with δTc-type pinning due to randomly-distributed defects that are larger than the coherence length ξ. The temperature dependence of the magnetic relaxation rate S exhibits a peak at a much lower temperature, which corresponds to a smaller pinning energy in the Ba0.55K0.45Fe2As2 superconductor. Moreover, the effective pinning potential Uo increases with increasing temperature and this behavior is in agreement with those of high-Tc cuprate superconductors.