Microstructure and Magnetization Investigations of Cu-Doping Effect on La₂CuO_4+δ Crystal

Measurement and characterization were carried out on Cu-doped and undoped La₂CuO_4+δ samples prepared under the same conditions. The magnetization measurement on the Cu-doped La₂CuO_4+δ sample shows coexistence of long-range antiferromagnetic order and superconductivity. A stripe-like structure was observed at room temperature on the ab-plane of Cu-doped La₂CuO_4+δ sample by transmission electron microscope. While for the undoped La₂CuO_4+δ sample no such behavior or structure feature was found. In this letter, these phenomena were discussed in terms of phase separation.