Thermally activated flux creep in the Gd(Ba2-xPrx)Cu3O7+δ system

The magnetoresistance of single-phase polycrystalline Gd(Ba2-xPrx)Cu3O7+delta samples has been studied within the thermally activated flux creep model. The decrease of pinning energy with applied magnetic field can be scaled to two power-law relations for magnetic fields, smaller and also larger than about I kOe. The derived H-c2(T), H-c2(0), and superconducting coherence length xi show that the Pr doping, similar to weak links, decreases the vortex flux pinning energy. It is also concluded that the substitution of Pr at the Ba site has a more destructive effect on the flux dynamics than Pr at the rare-earth site.