Magnetic properties and electronic conduction of superconducting La_2-xSr_xCuO₄

Magnetic susceptibility χ and resistivity were measured in La_2-xSr_xCuO₄. Enhancement of χ due to a ferromagnetic correlation, which is inherent in the orthorhombic phase at low Sr concentrations, disappears at around x=0.05, near the margin of the superconducting regime. In superconducting samples with 0.1≲x≲0.2, χ exhibits a broad peak at a temperature T_max. The T-dependent part of χ, χ^s(T), follows a single curve F regardless of x when χ^s and T are normalized with the peak value χ_max^s and T_max, as has been reported. However, the present scaling curve F decreases much more at T≪T_max than the reported one. The resistivity exhibits a T-linear dependence above a temperature T^* and deviates downward from the T-linear dependence below T^*. For x>0.1 the temperature T^* agrees well with T_max, indicating that the deviation from a T-linear resistivity is related to the decrease of χ below T_max. On the other hand, for x<0.1 a large reduction of χ is seen below ∼T^* in the data up to 1000 K by Yoshizaki et al., although no peak is seen in the χ-T curve. The T dependence of χ in La_2-xSr_xCu_1-yZn_yO₄ is also reported for x=0.16 and 0.22.