  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
