Resistivity and carrier mobility of the SmBa2Cu3O6+x superconductor with different oxygen doping levels

DC conductivity measurements between 15 and 300 K are reported for SmBa2Cu3 O6+x samples with different oxygen doping amounts (x) produced by annealing hinder appropriate high temperature and oxygen pressure conditions and que nching. Samples with x greater than or equal to 0.5 are superconductors: T(c)simila r to 60 K at x =0.7, T-c> 80 K at x=0.9. The transition from superconductio n to non-superconduction corresponds to the tetragonal to orthorhombic stru ctural transition and to the transition from semiconducting to metallic tem perature dependence of the resistivity. Oxygen doping causes a sudden increase of hole mobility near x=0.5. Below t his threshold, the behavior of the carrier mobility is in agreement with an Anderson localization.