Annealing effects on structural and magnetic properties of Co implanted ZnO single crystals

• Published in: Journal of applied physics 2011-04, Vol.109 (8), p.083918-083918-7
• Main Authors: Wikberg, J. M., Knut, R., Audren, A., Ottosson, M., Linnarsson, M. K., Karis, O., Hallén, A., Svedlindh, P.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry with specialization in Inorganic Chemistry; Engineering Science with specialization in Solid State Physics; FERROMAGNETISM; Fysik; Inorganic chemistry; Kemi; Kemi med inriktning mot oorganisk kemi; METAL; NATURAL SCIENCES; NATURVETENSKAP; Oorganisk kemi; OXIDES; Physics; Teknisk fysik med inriktning mot fasta tillståndets fysik
• ISSN: 0021-8979; 1089-7550; 1089-7550
• DOI: 10.1063/1.3559263

Single crystals of ZnO were implanted with 100 keV-Co ions at room temperature with a fluence of 4.8 × 10 16 cm −2 and subsequently annealed at different temperatures up to 800 ∘ C . The samples were analyzed by Rutherford backscattering spectrometry, secondary ion mass spectrometry, X-ray diffraction, X-ray photoemission spectroscopy and magnetometry. The as-implanted Co:ZnO crystal shows a homogeneous distribution of Co in the near surface region of the crystal. Upon annealing, clear evidence of secondary phases is found. At the highest annealing temperature ( 800 ∘ C ) a ferromagnetic behavior is observed at room temperature with a coercive field of 120 Oe assigned mainly to metallic fcc Co nano-crystallites. We find that for the annealed samples, the temperature dependent magnetization cannot be explained within a model containing only a paramagnetic contribution due to well dispersed Co ions and a ferromagnetic contribution due to Co nano-crystallites, at least one more ferromagnetic contribution is needed for a consistent explanation of the experimental results.