From A-type antiferromagnetism to ferromagnetism in half-doped perovskite manganites

Abstract We have studied by neutron diffraction, resistivity and magnetization measurements the variation of the structural, magnetic and electric properties as a function of the cation size mismatch at the perovskite A-site. The four selected compounds RE0.5AE0.5MnO3, with extremely large A-site cation size 〈rA〉=1.25–1.28 A, correspond to two 〈rA〉 values and for each 〈rA〉, two mismatch values have been retained. This study shows that the decrease of σ2 is an essential factor in stabilization of the ferromagnetism. As a result, the Curie temperature is markedly increased for the samples with smaller σ2, even if they exhibit a complex ferromagnetic/antiferromagnetic phase-separated state at low temperature.