Synthesis, Structural and Magnetic Properties of La 0.5 Ba 0.5 CoO 2.75+x

Hole doping to the Co 3+ ion in cobaltite perovskites can significantly modify the electromagnetic properties. We prepared the hole-doped cobaltite perovskites La 0.5 Ba 0.5 CoO 2.75+ x ( x = 0.06 and x = 0.15). Neutron powder diffraction and dc-magnetization experiments were performed to investigate the crystal structure and magnetic properties. We found that both of the samples have the cubic crystal structure with space group Pm 3 m in all the measured temperatures. Ferromagnetic transition occurs at 160K in x = 0.15 sample. For x = 0.06, we found the short-range ordered ferromagnetic state and a long-range ordered antiferromagnetic state coexist in low temperature.