Abstract
Polycrystalline SmMn1-xCoxO3 and Sm1-yRyMn0.6Co0.4O3, which have a single orthorhombic perovskite-type structure without any impurities, were prepared by complex polymerization to investigate the effects of A- and B-site element substitutions on the crystal structure and magnetic properties. The unit-cell volume of SmMn1-xCoxO3 decreased with increasing x and that of Sm1-yRyMn0.6Co0.4O3 increased with increasing average radius of A-site ions ⟨rR⟩, and the chemical pressure due to element substitution was observed in these two systems. At 0.0 ≤ x ≤ 0.4 in SmMn1-xCoxO3, a marked increase in the field-cooled magnetization MFC and an increase in the canted-antiferromagnetic transition temperature Tc were observed with increasing x, but they decreased for 0.5 ≤ x ≤ 1.0. However, no specific spin reversal phenomenon was observed, unlike in other RMnO3 compounds. The magnetic susceptibility of both compounds obeyed the Curie–Weiss law with constant susceptibility above 200 K, which was not common in other Sm compounds, and the effective magnetic moment Peff could be easily evaluated. By analyzing Peff of SmMn1-xCoxO3, we determined the electronic states of the ions constituting the sample as Mn3+(high spin, HS), Mn4+, and Co2+(HS) at 0 < x ≤ 0.5 and Mn4+, Co3+(low spin), and Co2+(HS) at 0.5 < x ≤ 0.9. The MFC of Sm1-yRyMn0.6Co0.4O3 decreased with increasing Y and Lu concentrations and increased with La concentration. The Tc and Weiss temperature of Sm1-yRyMn0.6Co0.4O3, both of which increased linearly with increasing ⟨rR⟩, could be attributed to the effects of chemical pressure. Although M − H measurements showed that Sm3+ in Sm1-yRyMn0.6Co0.4O3 was paramagnetic, the Peff analysis results suggested that the excited state of Sm3+ was affected.
Published Version
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