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 RE 0.5AE 0.5MnO 3, with extremely large A-site cation size 〈 r A〉=1.25–1.28 Å, correspond to two 〈 r A〉 values and for each 〈 r A〉, two mismatch values have been retained. This study shows that the decrease of σ 2 is an essential factor in stabilization of the ferromagnetism. As a result, the Curie temperature is markedly increased for the samples with smaller σ 2, even if they exhibit a complex ferromagnetic/antiferromagnetic phase-separated state at low temperature.