High-temperature magnetic order in dilute Cu²⁺ ions in LaCuO_3-δ

Electron paramagnetic resonance and magnetic susceptibility measurements in the tetragonally distorted metallic perovskite LaCuO3-δ with δ≈0.001 show that the highly diluted Cu2+ "impurities" interact ferromagnetically at long range and undergo a phase transition at an unusually high temperature of ∼ 240 K. © 1992.