Magnetic cobalt-ion substitution effect in electron-doped La1.89Ce0.11CuO4 superconductor

We investigate the in-plane transport and magnetic properties of La1.89Ce0.11(Cu1-xCox)O-4 thin films with x = 0.01-0.05. With increasing Co concentration, T-c is obviously suppressed and a crossover from superconductor to insulator at low temperature is observed, and the negative Hall coefficient is enhanced. All the Co-doped samples exhibit long-range ferromagnetic ordering even at the room temperature by magnetic measurements. (C) 2007 Elsevier B.V. All rights reserved.