The role of cationic disorder on the magnetic properties of double perovskites (Ca, Sr)(2-x)LaxFeIrO6

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We have synthesized polycrystalline samples of the series of double-perovskite (DP) type structure (Ca, Sr)(2-x)LaxFeIrO6. Their structural and magnetic properties were investigated by experiments of X-ray powder diffraction, magnetic susceptibility and electrical resistivity. Both series crystallize in a monoclinic structure, space group P2(1)/n (rather than in the triclinic I (1) over bar), with a significant degree of Fe/Ir cationic disorder. Interestingly, our results indicate a change in the nature of the microscopic magnetic interaction induced by La doping, where the system seems to evolve from antiferromagnetic in the extremities of the series, x = 0.0 and 2.0, to ferrimagnetic for intermediate regions of the series. In this work we focus on the comparison of the physical properties of two representative compounds of these families, Ca1.2La0.8FeIrO6 and Sr1.2La0.8FeIrO6, which exhibit the higher magnetization within their series. For the Ca-based sample the disorder is around similar to 34% while was found to be roughly similar to 22% for the Sr2-xLaxFeIrO6 compound. (c) 2009 Elsevier B.V. All rights reserved.4041932853288Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq