The effect of Cu-doping on the magnetic and transport properties of La0.7Sr0.3MnO3

The effects of Cu-doping on the structural, magnetic, and transport properties of La0.7Sr0.3Mn1−xCuxO3(0⩽x⩽0.20) have been studied using neutron diffraction, magnetization, and magnetoresistance (MR) measurements. All samples show the rhombohedral structure with the R3¯c space-group from 10 K to room temperature (RT). Neutron diffraction data suggest that some of the Cu ions have a Cu3+ state in these compounds. The substitution of Mn by Cu affects the Mn–O bond length and Mn–O–Mn bond angle resulting from the minimization of the distortion of the MnO6 octahedron. Resistivity measurements show that a metal to insulator transition occurs for the x⩾0.15 samples. The x=0.15 sample shows the highest MR(≈80%), which might result from the co-existence of Cu3+–Cu2+ and the dilution effect of Cu-doping on the double exchange interaction.