Insulator–metal transition in Nd0.8Na0.2Mn(1−x)CoxO3 perovskites |
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Authors: | E. Pollert, J. Hejtm nek, K. Kní ek, M. Maryko, J. P. Doumerc, J. C. Grenier,J. Etourneau |
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Affiliation: | a Institute of Physics, ASCR, 162 53, Praha 6, Czech Republic;b Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, 33608, Pessac, France |
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Abstract: | The electric and magnetic properties of the perovskites Nd0.8Na0.2Mn(1−x)CoxO3 (0x0.2) prepared by the usual ceramic procedure were investigated. The insulator-to-metal-like (IM) transition, closely related to a ferromagnetic arrangement, was revealed for the composition of x=0.04 and a similar tendency was detected for x=0. The insulating behavior persists down to low temperatures for higher contents of cobalt ions in spite of the transition to the bulk ferromagnetism. The properties are interpreted in terms of the steric distortion, tilting of the Mn(Co)O6 octahedra and the double-exchange interactions of the type Mn3+–O2−–Mn4+and Mn3.5+δ–O2−–Co2+, respectively. Presence of antiferromagnetic domains in the ferromagnetic matrix for the most of cobalt-substituted samples is supposed. |
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Keywords: | Manganese perovskites Insulator– metal transition |
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