Dominancy of antiferromagnetism in Zn1−xCoxO diluted magnetic semiconductors

• Published in: Journal of materials science 2011-03, Vol.46 (6), p.1830-1838
• Main Authors: Can, Musa Mutlu, Fırat, Tezer, Özcan, Şadan
• Format: Article
• Language: English
• Subjects: Abrasion; Abrasion resistance; Antiferromagnetism; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Lattices; Materials Science; Polymer Sciences; Scanning electron microscopy; Solid Mechanics; Spectroscopy; X-rays; Zinc oxide
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-010-5008-0

The outline of magnetic interactions in DMSs was determined using Zn 1− x Co x O particles, where “ x ” was changed as 0.01, 0.05, 0.10, 0.15, and 0.20. The syntheses were accomplished though mechanical milling and thermal treatment, known as solid state reaction. The formation of each synthesis was monitored by differential thermal and thermo gravimetric methods (DT-TGA). Substitution of Co 2+ ions with Zn 2+ host atoms in a ZnO lattice was analyzed using X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectrometry (EDS) data, transmission electron microscopy (TEM) figures, scanning area electron diffraction (SAED) patterns, and X-ray photo spectroscopy (XPS) spectrum. The measured Co contents in ZnO lattice were found to be ~0.7% less than the expected result. In addition to Zn 1− x Co x O particles, tungsten (W) contaminations were noticed in the variations of 1.5 ± 0.2%, as originating from the abrasion between the miller and balls. The progressive replacement of Co 2+ with Zn 2+ host ions in ZnO lattice from 1% to 20% decreased the band edge from 3.03 ± 0.01 eV to 2.95 ± 0.01 eV, respectively. Co doping has also changed the magnetic nature of the ZnO. Although having both interactions (ferromagnetic and antiferromagnetic), dominance of ferromagnetic behavior was only observed for Zn 0.99 Co 0.01 O with the coercivity of ~154 ± 50 Oe and positive Curie–Weiss temperature as 79 ± 1 K. However, the calculated values have proved that the higher Co 2+ concentrations in ZnO lattice have increased the efficiency of antiferromagnetic interactions. Surprisingly, there was no rapid change at values as mentioned in previous works.