SCHEDULED MAINTENANCE
Ti-rich double perovskites LnCu3−yTi2−xMn2+x+yO12: ferrimagnetism and magnetoresistance up to room temperature
Abstract
Ti-rich double perovskites LnCu3−yTi2−xMn2+x+yO12 have been synthesized at normal pressure, with a wide homogeneity range, 0 < x < 0.5 and 0 < y ≤ 1. All these oxides are ferrimagnetic, with TC ranging from 160 K to 293 K, in spite of the high 3d0-Ti content in the octahedral sites. The evolution of TC can be monitored on the basis of three factors-antiferromagnetic superexchange interactions Cu2+↑–O–Mn3+/4+↓–O–Cu2+↑, double exchange Mn4+–O–Mn3+ interactions in the octahedral sites and chemical pressure due to the size effect of Ln3+. Differently from high pressure synthesized manganites, these oxides exhibit maximum magnetoresistance at TC, similar to single perovskite manganites. Intrinsic magnetoresistance can thus be obtained at room temperature, but with a smaller amplitude compared to single manganites, due to the dilution effect of titanium.
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