Magnetic dynamics of NiMn2O4 spinel produced by a simple aqueous sol–gel route
| Autor: | A.J. Freitas Cabral, Helio Salim de Amorim, B. R. Salles, C.M. Rocha Remédios, Miguel A. Novak, J.D. Peña Serna |
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| Rok vydání: | 2021 |
| Předmět: |
Phase transition
Materials science Rietveld refinement Analytical chemistry Condensed Matter Physics Manganite Electronic Optical and Magnetic Materials Condensed Matter::Materials Science Magnetization Exchange bias Ferromagnetism Curie temperature Antiferromagnetism Condensed Matter::Strongly Correlated Electrons |
| Zdroj: | Journal of Magnetism and Magnetic Materials. 538:168291 |
| ISSN: | 0304-8853 |
| Popis: | Polycrystalline nickel manganite was prepared by a simple sol–gel method from an aqueous solution of metal chlorides containing sorbitol as a chelating agent. X-ray diffraction and Rietveld refinement show a spinel-type crystalline structure, space group Fd 3 ¯ m, and a minor ( ~ 3%) phase of rock salt structure assigned to NiO. XPS measurement shows a typical manganite electronic structure with Mn in the oxidation states Mn2+, Mn3+, and Mn4+. The zero-field-cooled and field-cooled magnetization curves measured under low magnetic fields display irreversibility and an asymmetric hysteresis evidencing some exchange bias. Field dependent DC susceptibility above Curie temperature put into evidence a competition of short ranged ferro and antiferromagnetic interactions. AC in-phase susceptibility shows a frequency independent sharp peak at the ferromagnetic phase transition (97 K) and a broad maximum at lower temperature. These maxima show a weak frequency dependence in the out-phase component. Cole–Cole plot reveals at least two magnetic relaxation processes. |
| Databáze: | OpenAIRE |
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