Infield superconductivity of carbon nanotubes-Cu0.5Tl0.5Ba2Ca2Cu3O10−δ superconductor composites

Abstract

We investigated the infield superconducting properties of carbon nanotubes-Cu0.5Tl0.5Ba2Ca2Cu3O10−δ superconductor {(CNTs)x-(CuTl-1223)}; x = 0∼7 wt.% composites. The zero resistivity critical temperature {Tc(0)}, critical superconducting onset transition temperature {Tconset(K)} and glass transition temperature (Tg) have been shifted towards lower values after the addition of carbon nanotubes (CNTs). The double transitions for all concentration of CNTs have indicated the existence of vortex-glass phase. The significant resistive broadening {ΔT = Tconset(K)-Tc(0)} has been observed with increasing values of external applied magnetic field. The more increasing trend in resistive broadening has also been observed after the addition of CNTs in CuTl-1223 matrix. The magnetic field dependent activation energy Uo (H) has been calculated according to thermally activated flux flow (TAFF) model. The overall decreasing rate in pinning energy could be due to diffusion of carbon across the grain-boundaries.