Magnetic and transport properties of La0.7Cd0.3(Mn0.9TM0.1)O-3 transition metal doped manganites

In this work we present structural and magnetic properties of La0.7Cd0.3Mn0 .9Tm0.1O3 (TM=Fe, Co, Ni) manganites. Samples were prepared by the sol-gel low temperature method. preliminary room temperature structural characteriz ation of these compounds shows a mixture of rhombohedral (R (3) over barc) and orthorhombic (Pnma) phases. The low value of the tolerance factor alrea dy indicates a distorted structure of the perovskite cell. Different kinds of magnetic interactions have been observed as the doping TM element is cha nged. Thus, respect to the undoped La0.7Cd0.3MnO3 composition, the Curie te mperature decreases for the Fe doped sample, but progressively increases as Mn ions are substituted by Co or Ni, respectively. The measured low temper ature magnetic moment values are interpreted in terms of ferro- (for the Co and Ni doped samples) or antiferromagnetic (for the Fe doped sample TM3+-M n3+/Mn4+ interactions. Despite their ferromagnetic character, all compositi ons show insulating behaviour in the whole temperature range studied. (C) 2 001 Elsevier Science B.V. All rights reserved.