Ferromagnetic Gd-implanted ZnO single crystals

In order to introduce ferromagnetic properties, ZnO single crystals have been implanted with Gd ions at 180 keV ion energy and two different fluences. Magnetization reversal hysteresis loops have been recorded for as-implanted as well as annealed samples using a superconducting quantum interference device (SQUID). It was found that for a fluence of 5x1015 Gd+/cm2 post implantation annealing leads to an increase of the saturation moment up to 1.8 B/Gd at exactly 300 K thus excluding Gd, ZnGd or Gd2O3 secondary phases to be formed. The increase of the saturation moment can be explained along with changes in resistivity due to the annealing reported elsewhere.