  Increasing doping concentration (x) in Pnictide superconductors results in
the suppression of long range magnetic order and the emergence of
superconductivity. While doping destroys long range magnetic order however the
effect if any of the surviving magnetic fluctuations on superconductivity in
Pnictides is currently not well understood. In optimally doped BaFe2-xCoxAs2
single crystals, below Tc we observe local regions with positive magnetization
coexisting along with superconductivity at low applied magnetic fields (H).
With increasing H the positive magnetization response gets weaker and the
robust superconducting diamagnetic response appears. The normal state is found
to be inhomogeneous with regions having local diamagnetic response embedded in
a positive magnetization background. Estimates of the superconducting fraction
in the normal state shows it maximizes for the optimally doped crystal. We
construct a doping dependent H - T diagram identifying different fluctuation
regimes and our data suggests a close correlation between magnetic and
superconducting fluctuations in BaFe2-xCoxAs2.
