THE GD CONCENTRATION DEPENDENCE OF THE MAGNETIC PROPERTIES OF ROOM TEMPERATURE FERROMAGNETIC ZNO:GD SEMICONDUCTOR

We present structural and magnetic properties of ZnO films doped with rare-earth Gd ions at various concentrations, achieved by ion implantation technique and pulsed laser deposition (PLD) on ZnO (0001) single crystals and sapphire. X-ray diffraction shows Gd doping in ZnO and crystal quality degrades with increasing Gd concentration. Magnetization as a function of temperature revealed a positive magnetization at 305 K and a concave trend was observed for all samples for both implanted and PLD grown samples. The highest saturation magnetization was achieved for Gd concentration of x = 7.9 % (0.7 µB/Gd) and at dosage of 9.0 × 1015cm-2 (2.6 µB/Gd) for the PLD grown and implanted samples, respectively. We believe that the Gd ion solubility limit in the implanted and PLD grown samples, of around 3% and 7.9%, respectively, are reached.