One-Dimensional Conductivity and Resistivity Anomaly Observed in La_8-xSr_xCu₈O₂₀ Single Crystals

Abstract

Single crystals of La_8-xSr_xCu₈CO₂₀ (1.0≤x≤1.8) have been grown using the CuO flux method in a flowing O₂ atmosphere. Resistivities parallel to the c-axis ρ_//c and perpendicular to the c-axis ρ_⊥c each show an anomaly around 140 K. The anisotropy ρ_⊥c /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 H⊥c show a cusp-like anomaly around 140 K, suggesting the occurrence of a magnetic phase transition.