La2CuO4
La2CuO4 is a copper oxide compound that serves as the parent compound of the La-based cuprate superconductors, such as La2−xSrxCuO4. It crystallizes in the K2NiF4-type layered perovskite structure, consisting of CuO2 planes separated by LaO layers. In this structure copper is formally Cu2+, and the spins in the CuO2 planes form a two-dimensional spin-1/2 antiferromagnetic lattice. The undoped material is a Mott insulator of the charge-transfer type, with strong electron correlations that localize carriers on copper sites.
At high temperature the crystal system is tetragonal; upon cooling it undergoes a structural distortion to
Doping with divalent cations such as Sr2+ or Ba2+ substitutes for La3+ and introduces holes into the
La2CuO4 is widely studied as a benchmark system for understanding correlation-driven physics in copper oxide superconductors