Excess conductivity of Pb-doped (Cu0.5−xPbxTl0.5)Ba2Ca2Cu3O10−δ superconductors

► The excess conductivity analysis of (Cu0.5−xPbxTl0.5)-1223 superconductors are performed in the light of AL theory. ► The coherence length [ξc(0)] has shown a decreasing trend with the increase of Tc(0). ► The fluctuation pairs are formed both due to electron-phonon and electron-electron correlations in (Cu0.5−xPbxTl0.5)-1223.