Magnetic properties of transition metal-implanted ZnO nanotips grown on Sapphire and Quartz

초록

ZnO nanotips, grown on c-Al<inf>2</inf>O<inf>3</inf> and quartz, were implanted variously with 200 keV Fe or Mn ions to a dose level of 5 × 1016 cm-2. The magnetic properties of these samples were measured using a superconducting quantum interference device (SQUID) magnetometer. Fe-implanted ZnO nanotips grown on c-Al<inf>2</inf>O<inf>3</inf> showed a coercive field width of 209 Oe and a remanent field of 12% of the saturation magnetization (2.3 × 10-5 emu) at 300 K for a sample annealed at 700°C for 20 minutes. The field-cooled and the zero-field-cooled magnetization measurements also showed evidence of ferromagnetism in this sample with an estimated Curie temperature of around 350 K. The Mn-implanted ZnO nanotips grown on c-Al<inf>2</inf>O<inf>3</inf> showed superparamagnetism resulting from the dominance of a spin-glass phase. The ZnO nanotips grown on quartz and implanted with Fe or Mn showed signs of ferromagnetism, but neither was consistent. © 2008 Journal of Magnetics.

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