Anisotropic conductivity and its anomalies in la_8-xsr_xcu₈o₂₀ single crystals

Single crystals of La_8-xSr_xCu₈O₂₀ (1.0≤a≤1.8) are grown using the CuO flux method in a flowing O₂ atmosphere. Resistivities parallel to the c-axis, ρ_Tc, and perpendicular to the c-axis, each show an anomaly around 140 K. The anisotropy ρ_Tc/ρ_c increases from 5 ˜ 10 at room temperature to 8 - 20 at 5 K. These La_8-xSr_xCu₈O₂₀ crystals can be considered quasi-one-dimensional conductors. Magnetic susceptibilities for both H//c and HTc show a cusplike anomaly around 140 K, suggesting the occurrence of a magnetic phase transition.