Thermal Fluctuations of $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z}$ Bulk Superconductor

We report on the critical fluctuations from the magnetoresistance measurements in polycrystalline $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z}$ superconductor. The critical exponents have been calculated above the critical temperature $T_{c}$ as well as in the temperatures interval close to the zero resistance critical temperature. Above $T_{c}$ only Gaussian fluctuations have been observed in a three-dimensional fluctuating system. Additionally, far above $T_{c}$ the applied magnetic field induces the crossover from 3D to 2D fluctuating system. At the temperatures range close to the zero critical temperature the properties of the weak links are dominating and the fluctuating phase in each grain becomes long-range ordered as a consequence of the activation of weak links between grains.