EFFECTS OF OXYGEN NONSTOICHIOMETRY ON THE ANISOTROPIC RESISTIVITY IN BI2SR2CACU2O8+X

Resistivity components parallel and perpendicular to the CuO2 plane have been measured in Bi2Sr2CaCu2O8+x single crystals. The oxygen content x is systematically varied by annealing with oxygen at pressures over the range 10(-5)<p<1 bar with temperature fixed at 400-degrees-C. A variation of the critical temperature is observed as a function of oxygen annealing pressure p, consistent with the result on polycrystals. With increasing p, the magnitude of the in-plane resistivity rho(ab) diminishes, keeping an almost linear temperature dependence. In contrast, the semiconductor-like temperature dependence of the out-of-plane resistivity rho(c) is significantly affected by oxygen intercalation. The functional form of the rho(c)-T curve supports the tunneling process for the out-of-plane conduction mechanism.