Structure,Magnetic and Electric Properties of Layered Perovskite LaSr_2Mn_(2-x)Cu_xO_7

Layered perovskite LaSr_2Mn_(2-x)Cu_xO_7 polycrystalline samples were prepared by solid state reaction.Structure and magnetic as well as electric properties were investigated by X-ray diffraction, superconductor quantum interference device and direct current four probe method.The samples have the single phase with layered perovskite structure and the space group is I4/mmm.The substitution of 10% copper destroys the charge order of LaSr_2Mn_2O_7.Characteristic spin glass state occurs on the LaSr_2Mn_(2-x)Cu_xO_7,and the spin frozen temperature is near 225K.The electric properties show that the LaSr_2Mn_2O_7 sample's conduction characters are influenced by the substitution of 10% Cu,which keeps in the insulator state from 77K to room temperature.At the same time,transport properties are changed by the substitution of 10% copper.