Synthesis and Excess Conductivity Analyses of Ce-Doped Tl1−x Ce x Ba2Ca2Cu3O10−δ Superconductors

Abstract

The role of mobile carriers density supplied by TlBa 2O4−δ charge reservoir layer is investigated by doping Ce in TlBa 2Ca 2Cu 3O10−δ superconductors. The T c(onset) and T c(R= 0) versus Ce contents have shown almost a parabolic-shaped phase diagram which is interpreted in terms of hole’s doping. The magnetic measurements showed that magnitude of diamagnetism is gradually suppressed with Ce doping at Tl site. Fourier transform infrared (FTIR) revealed that the phonon modes associated with apical oxygen atoms type Cu(2)–O A–Tl are softened, whereas the planar oxygen modes are hardened with the doping of Ce the unit cell. In the excess conductivity, analyses of conductivity data of Tl 1−xCe xBa 2Ca 2Cu 3O10−δ samples have shown a suppression of T cmf(K) and the width of 2D conductivity regimes, whereas the coherence length along the c-axis ξc(0) and the interlayer coupling J are enhanced with the doping of Ce +4 in the charge reservoir. The increase in ξc(0) is interpreted in the form of homogenization of the carrier’s density of carriers the CuO 2 planes. The process of homogenization is accomplished with the reduction of density of carriers in the outer CuO 2 that consequently promotes increase in the phase relaxation time, τϕ, of the carriers, their Fermi velocity, and the energy required to break apart the Cooper pairs.