Competition between the charge ordered and ferromagnetic states in (La,Nd)0.75Na0.25MnO3 manganites
نویسندگان
چکیده
Structural, magnetic, and transport properties of (La1−xNdx )0.75Na0.25MnO3 (0 x 1) are studied. The system exhibits a rhombohedrally distorted perovskite structure for x 0.2 and it convert to an orthorhombic structure for x 0.4. Re-entrant ferromagnetic type charge ordering transitions are observed in the narrow bandwidth samples (x 0.6), while charge ordering transition is not observed for these samples with rhombohedral structure. Combining with the published results related to the charge ordering transition, we argue that the rhombohedral structure likely favor double exchange interaction and suppress charge ordering interaction. The compounds show metal to insulator transitions except Nd0.75Na0.25MnO3. The resistivity data above the metal to insulator transition temperature for the charge ordered sample are discussed in the frame work of variablerange hopping model. 2004 Elsevier B.V. All rights reserved. PACS: 75.47.Lx; 75.47.Gk; 75.30.Kz
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