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

The effects of praseodymium doping on the excess conductivity sigma'(T) and pseudogap (PG) Delta*(T) in Y1-xPrxBa2Cu3O7-delta 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 T-c drops. At the same time the shape of the rho(T) curves changes from metallic (x <= 0.34) to one that is typical for weakly doped YBa2Cu3O7-delta single crystals with a characteristic thermally activated deflection (x > 0.34). Regardless of the value of x, close to T-c, sigma'(T) is well described by the Aslamazov-Larkin and Maki-Thompson theories, demonstrating a 3D-2D crossover with increasing temperature. The crossover temperature T-0 makes it possible to determine the coherence length along the c axis, xi(c)(0). At x = 0, Delta*(T) displays a maximum at T-pair approximate to 110 R that is typical for YBCO films. As x increases the maximum at T-pair is washed out, but a pronounced maximum Delta*(T) in the high temperature region appears, followed by a linear section with a positive slope. Such a dependence Delta*(T) is normal for magnetic superconductors and is, most likely, caused by the influence of the intrinsic magnetic moment of Pr (mu(Pr) approximate to 4 mu(B)). Published by AIP Publishing.