Effect of A-site average radius and cation disorder on magnetism and electronic properties in manganite \(\hbox {La}_{0.6}\hbox {A}_{0.1}\hbox {Sr}_{0.3}\hbox {MnO}_{3}\) (A = Sm, Dy, Er)

The magnetism and electronic transport properties of \(\hbox {La}_{0.6}\hbox {A}_{0.1}\hbox {Sr}_{0.3}\hbox {MnO}_{3}\) (A = Sm, Dy, Er) are studied by the measurements of magnetization and resistivity. Infrared spectra reveal that two typical absorbed peaks occur in their corresponding positions. However, the stretching mode \(\nu _{3}\) exhibits an obvious shift to low frequency and its intensity gets enhanced in Dy- and Er-doping samples. In Raman spectra, the stretching mode shows the same shift, while the Jahn–Teller mode remains invariant. The A-site substitution with other elements changes the average ionic radius and induces cation disorder, causing a decrease of the Curie temperature and the formation of spin–cluster-glass. Except for Sm-doping sample, the field dependence of magnetization at different temperatures shows a similar magnetization process indicating that the low concentration substitution with 10 % magnetic ions cannot signally influence the magnetic exchange interaction on B-site sublattice. Based on the analysis of electronic transport in metallic regime, we find that the main factor for impacting the electronic transport is from the variation of crystal lattice and the induced cationic disorder, regardless of magnetic or non-magnetic substitution.