A study on the transport properties in the Bi_2-xPb_xSr_1.65La_0.35CuO_y system

Samples of the Bi_2-xPb_xSr_1.65La_0.35CuO_y (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.6) system with different oxygen concentration are obtained. The analysis of x-ray diffraction indicates that a tetragonal-orthorhombic transition takes place with increase of Pb content. The resistivity measurement shows that for the quenched samples the highest T^onset_c is 35 K, and T⁰_c (zero resistivity) is 25 K; while for the samples annealed under low oxygen partial pressure, the highest T^onset_c and T⁰_c increase to 45 K and 37 K, respectively. Moreover, the phenomenon of a spin gap is systematically observed in this system. The analysis of the experimental results reveals that the microstructural characteristic of the Bi2201 system is closely related to both the spin-paring and superconductivity. The dominated spin scattering mechanism is suggested as the origin of the T-linear resistivity.