Troyanchuk, I.O.; Bushinsky, M.V.; Tereshko, N.V.; Dobryanskii, V.M.; Sikolenko, V.; Többens, D.M.: Magnetic properties of manganites doped with gallium, iron, and chromium ions. Journal of Experimental and Theoretical Physics 120 (2015), p. 838-843
10.1134/S1063776115040160

Abstract:
The magnetization and the crystal structure of the La0.7Sr0.3Mn1 − x M x O3 (M = Ga, Fe, Cr; x ≤ 0.3) systems are studied. The substitution of gallium and chromium is shown to cause phase separation into antiferromagnetic and ferromagnetic phases, whereas the substitution of iron for manganese stabilizes a spinglass state. The ferromagnetic phase in the chromium-substituted compositions is much more stable than that in the case of substitution by iron ions or diamagnetic gallium ions. The magnetic properties are explained in terms of the model of superexchange interactions and the localization of most e g electrons of manganese. The stabilization of ferromagnetism in the chromium-substituted compositions can be caused by the fact that the positive and negative contributions to the superexchange interaction between Mn3+ and Cr3+ ions are close to each other but the antiferromagnetic part of the exchange is predominant. Moreover, some chromium ions are in the tetravalent state, which maintains the optimum doping conditions.