A comparison between ZnO films doped with 3d and 4f magnetic ions

We present electrical and magnetic properties of ZnO films doped with 3d (Mn) and 4f (Gd or Nd) magnetic ions grown on a-plane Al2O3 substrates. Both for films doped with 3d magnetic ions and for films doped with 4f magnetic ions, Hall investigations revealed that the carrier concentration decreases and the resistivity increases with increasing the oxygen partial pressure during the pulsed laser deposition growth, probably because the formation of oxygen vacancies is hindered. Measurements of magnetic properties revealed ferromagnetism above room temperature with magnetic moments up to 0.2 μB/Mn ion in insulating ZnO:Mn films co-doped with 0.1% P and up to 0.3 μB/Gd ion in nconducting ZnO:Gd films co-doped with 0.2% Al.