LSCO

LSCO refers to the copper oxide superconductor La2−xSrxCuO4, a member of the cuprate family. In this material, strontium substitutes for lanthanum to introduce holes into the CuO2 planes, enabling superconductivity once a sufficient doping level is reached. The chemical composition is expressed as La2−xSrxCuO4, with x commonly in the range about 0.05 to 0.3.

Crystal structure: LSCO adopts a layered perovskite structure related to the K2NiF4 type, consisting of CuO2 planes separated by layers containing La and Sr. The copper centers form corner-sharing CuO6 octahedra, and superconductivity is believed to originate primarily in the CuO2 planes. The material shows significant anisotropy between in-plane and out-of-plane properties.

Phase diagram and properties: The undoped La2CuO4 is a Mott insulator with antiferromagnetic order. Substituting Sr suppresses the antiferromagnetism and induces superconductivity for roughly 5–30% Sr. The superconducting transition temperature Tc reaches a maximum near x ≈ 0.15, about 37–38 K, and decreases for higher or lower doping. The underdoped region exhibits a pseudogap and unusual normal-state behavior.

Discovery and impact: High-temperature superconductivity in LSCO is part of the broader cuprate family discovered in the late 1980s. LSCO has been extensively studied as a canonical hole-doped cuprate, contributing to understanding superconductivity, magnetism, and correlated electron phenomena in layered oxides.

Applications and research use: While not used for large-scale power applications due to its relatively modest Tc, LSCO and related cuprates are central to fundamental research. Thin films and single crystals serve in spectroscopic studies and in prototype superconducting devices, including Josephson junctions and sensors.