Structural, magnetic and magnetotransport properties of La0.7−xCexBa0.3MnO3 (x = 0.0–0.4)

Structural, magnetic and magnetotransport properties of La0.7−xCexBa0.3MnO3 (x = 0–0.4) have been investigated although some unreacted secondary phases of CeO2 were present. The rhombohedral structure (R-3c) forx = 0 transforms to orthorhombic with the space groupImma forx = 0.3. All samples showed ferromagnetic transition above 300 K and a negative magnetoresistance. For x>0.1, magnetization data measured at 1 T showed a decrease at low temperatures (T < 50 K) due to antiferro-magnetic coupling between Ce-local moments and Mn-moments. Forx = 0.4, the resistivity showed a maximum around 200 K which corresponds to ordering temperature of cerium. Since these results are similar to that observed in the Sr-containing La0.5−xCexSr0.5MnO3 (x = 0–0.4) system, we suggest that the cerium ions are in the trivalent state and the anomalous behaviour has been attributed to a Kondo-like effect.