Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1803387 | Journal of Magnetism and Magnetic Materials | 2006 | 4 Pages |
The measurements of temperature dependence of electrical resistivity ρ(T)ρ(T) and magnetic susceptibility χ(T)χ(T) as well as neutron diffraction studies were performed for three groups of R1-xSrxMnO3R1-xSrxMnO3 manganites. Each group was characterized by the same average ionic radius 〈rA〉〈rA〉 of rare earth R, but by different degree of cation disorder σ2=xiri2-〈rA〉2. For each composition, the isotope-substituted samples (O16→O18) were also prepared. It was shown that the increase in σ2σ2 at fixed 〈rA〉〈rA〉 leads to appreciable changes in electrical and magnetic properties, as well as to a more pronounced isotope effect. Large values of σ2σ2 give rise to a significant scatter in the values of the electron hopping integral for neighboring Mn sites. This favors the electron localization and the tendency to antiferromagnetism in the phase-separated state, thus enhancing the effect of oxygen isotope substitution.