Conduction mechanism in Pr‐doped GdBa ₂ Cu ₃ O ₇

Abstract

The normal state resistivity of single phase polycrystalline Gd(Ba2−xPrx)Cu3O7+δ samples with 0.0 ≤ x ≤ 0.50 have been investigated. The two-dimensional variable range hopping is dominant in the normal state resistivity of the samples. The conduction shows that Pr-doping strongly localizes the carriers in normal state, and finally causes the suppression of superconductivity. Based on the resistivity measurements, the effect of Pr substitution in 123 structure of HTSC at Gd or Ba site is to increase the pseudogap temperature Ts, although, Pr at Ba site has a stronger effect on the suppression of Ts and superconductivity. Pr-doping not only reduces the carrier density and induces pseudogap, but also simultaneously increases Ts and suppresses the linearity behavior of resistivity vs. temperature in the normal state. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)