Carrier concentrations in Bi2Sr2-zLazCuO6+δ single crystals and their relation to the Hall coefficient and thermopower

We measured the thermopower S and the Hall coefficients R-H of Bi2Sr2-zLazCuO6+delta (BSLCO) single crystals in a wide doping range, in an effort to identify the actual hole concentrations per Cu, p, in this system. It is found that the universal relation between the room-temperature thermopower and T-c does not hold in the BSLCO system. Instead, comparison of the temperature-dependent R-H data with other cuprate systems is used as a tool to identify the actual p value. To justify this approach, we compare normalized R-H(T) data of BSLCO, La2-xSrxCuO4 (LSCO), YBa2Cu3Oy, and Tl2Ba2CuO6+delta, and demonstrate that the R-H(T) data of the LSCO system can be used as a template for the estimation of p. The resulting phase diagram of p vs T-c suggests that T-c is anomalously suppressed in the underdoped samples, becoming zero at around p similar or equal to 0.10, while the optimum T-c is achieved at p similar or equal to 0.16 as expected.