Pseudogap and fluctuation conductivity in Y1-xPrxBa2Cu3O7-δ single crystals with different concentrations of praseodymium

The effects of praseodymium doping on the excess conductivity σ′(T) and pseudogap (PG) Δ*(T) in Y1–xPrxBa2Cu3O7–δ single crystals with a change in the Pr concentration from x = 0 to x = 0.43 are presented. It is found that as x increases the resistance of the samples increases, whereas the critical temperature Tc drops. At the same time the shape of the ρ(T) curves changes from metallic (x ≤ 0.34) to one that is typical for weakly doped YBa2Cu3O7–δ single crystals with a characteristic thermally activated deflection (x > 0.34). Regardless of the value of x, close to Tc, σ′(T) is well described by the Aslamazov-Larkin and Maki-Thompson theories, demonstrating a 3D-2D crossover with increasing temperature. The crossover temperature T0 makes it possible to determine the coherence length along the c axis, ξc(0). At x = 0, Δ*(T) displays a maximum at Tpair ≈ 110 К that is typical for YBCO films. As x increases the maximum at Tpair is washed out, but a pronounced maximum Δ*(T) in the high temperature region app...