Ac and dc magnetotransport properties of the phase-separated La0.6Y0.1Ca0.3MnO3 manganite

• Published in: Journal of materials science 2008, Vol.43 (2), p.503-509
• Main Authors: Fonseca, F. C, Souza, J. A, Muccillo, E. N. S, Muccillo, R, Jardim, R. F
• Format: Article
• Language: English
• Subjects: ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Crystallography and Scattering Methods; dielectric spectroscopy; Direct current; electrical resistance; electron microscopy; Exact sciences and technology; Ferromagnetism; Grain size; Insulators; Magnetic fields; Magnetic properties; Magnetic properties and materials; Magnetism; Magnetoresistance; Magnetoresistivity; Magnetotransport phenomena, materials for magnetotransport; Manganites; Materials Science; Physical properties; Physics; Polymer Sciences; scanning electron microscopy; Sol-gel processes; sol-gel processing; Solid Mechanics; temperature; Transport properties; X-ray diffraction
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-007-1822-4

The physical properties of the La₀.₆Y₀.₁Ca₀.₃MnO₃ compound have been investigated, focusing on the magnetoresistance phenomenon studied by both dc and ac electrical transport measurements. X-ray diffraction and scanning electron microscopy analysis of ceramic samples prepared by the sol–gel method revealed that specimens are single phase and have average grain size of ∼0.5 μm. Magnetization and 4-probe dc electrical resistivity ρ(T,H) experiments showed that a ferromagnetic transition at T C ∼ 170 K is closely related to a metal-insulator (MI) transition occurring at essentially the same temperature T MI . The magnetoresistance effect was found to be more pronounced at low applied fields (H ≤ 2.5 T) and temperatures close to the MI transition. The ac electrical transport was investigated by impedance spectroscopy Z(f,T,H) under applied magnetic field H up to 1 T. The Z(f,T,H) data exhibited two well-defined relaxation processes that exhibit different behaviors depending on the temperature and applied magnetic field. Pronounced effects were observed close to T C and were associated with the coexistence of clusters with different electronic and magnetic properties. In addition, the appreciable decrease of the electrical permittivity ε′(T,H) is consistent with changes in the concentration of e g mobile holes, a feature much more pronounced close to T C .