Magnetic properties of ZnO nanotips ion-implanted with Fe or Mn

ZnO nanotips grown on quartz, sapphire, and glass were implanted with Fe or Mn to a dose of 5 $\times $ 10$^{16}$ ions/cm$^{2}$ and subsequently annealed at temperatures from 575 to 800$^{\circ}$C in O$_{2}$ flowing at 25 sccm. This experiment was undertaken in an attempt to create dilute magnetic semiconductors with ferromagnetic properties persisting to room temperature. After implantation and annealing, the samples were characterized by field and temperature dependent magnetization measurements in a SQUID magnetometer and photoluminescence. All of the samples demonstrated signatures of ferromagnetism (coercive and remanent fields in hysteresis measurements), but not all manifest an optimal annealing temperature. PL measurements are used to detect implant damage recovery and the incorporation of the implanted transition metal into the ZnO nanotips.