High intrinsic flux pinning strength of BaFe2-xCoxAs2 superconductor

The field dependence of flux pinning potential, U0, for under-doped, optimally doped and over-doped Ba(Fe,Co)2As2 single crystals has been investigated. U0 is determined using the Thermally Activated Flux Flow (TAFF) model, for both H || ab and H || c configurations. The observed power law dependencies of U0 versus H suggest that for fields upto 12 T for H || ab and 7 T for H || c, individual flux pinning, and for fields beyond 7 T for H || c, collective pinning becomes operative. A comparison of U0 for the Ba(Fe,Co)2As2 system with some other superconductors is presented