Addition of Co nanoparticles has not affected the crystal structure of host CuTl-1223 phase.
Activation energy was decreased for all concentrations of Co nanoparticles in host CuTl-1223.
Magnetic nature of Co nanoparticles has slowed down the flux creep in CuTl-1223 matrix.
Flux line lattice and size of nanoparticles be comparable to coherence length for efficient pinning.