Magnetic interactions in Co2+ doped ZnO synthesised by co-precipitation method: Efficient effect of hydrogenation on the long-range ferromagnetic order
| Autor: | Z.J. Yacoob, M. El-Hilo, A.A. Dakhel |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Materials science Doping Analytical chemistry chemistry.chemical_element 02 engineering and technology Zinc 021001 nanoscience & nanotechnology Condensed Matter Physics Polaron 01 natural sciences Electronic Optical and Magnetic Materials Condensed Matter::Materials Science Paramagnetism chemistry Ferromagnetism 0103 physical sciences 0210 nano-technology Cobalt Solid solution Wurtzite crystal structure |
| Zdroj: | Journal of Magnetism and Magnetic Materials. 482:125-134 |
| ISSN: | 0304-8853 |
| Popis: | Zinc oxide doped with different concentrations of Co2+ ions (ZnO:Co) nano-powders were synthesised by co-precipitation method using complexes zinc acetate dihydrate and cobalt acetylacetonate. The mass ratios of Co/Cd in the investigated samples were 0.5% 1%, 2%, and 3%. The X-ray diffraction (XRD) study confirmed the formation of single-phase crystalline hexagonal Wurtzite structure, thus, Co ions were successfully doped into ZnO lattice forming substitutional solid solutions. The purpose of the present study is to synthesise and investigate the possible creation of room-temperature ferromagnetic (RT-FM) properties in host ZnO for DMS applications. The magnetic analysis has showed that the magnetic behavior of the as prepared ZnO:Co samples is dominated by a paramagnetic component over ferromagnetic component, which is an indicative of dominant uncoupled Co spins. However, the same samples exhibited pronounce room temperature ferromagnetic behavior (RTFM) when they were hydrogenated, which was attributed to the role of oxygen vacancies (VO) in accordance with the Bound Magnetic Polaron Model (BMP). Furthermore, the analysis of the magnetization reversal via fluctuation fields for the hydrogenated samples shows that the distribution of activation energies arises from both, the dispersion of anisotropy fields and the sizes distribution of FM ordered regions. Due to the dispersion of anisotropy fields, the mediated exchange coupling through vacancies at low ions concentrations provide stronger RTFM behavior than the highly concentrated ones. Accordingly, it believed that increasing the ions concentrations to enhance the direct ions coupling may destabilize the polarons structure and then weaken the irreversible magnetic behavior. |
| Databáze: | OpenAIRE |
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