Magnetic properties of Ni-implanted ITO thin films

摘要

The magnetic properties of Ni-implanted ITO thin films have been investigated by ferromagnetic resonance (FMR) technique and vibrating sample magnetometry (VSM) techniques. Commercially available ITO thin films on fused silica substrates have been implanted with different fluences of Ni~+ ions with energy of 40 keV and ion current density of 8 μA/cm~2 at room temperature. The samples with three doses of 0.5 × 10~(17), 1.0 × 10~(17) and 1.5 × 10~(17) ions/cm~2 have been studied. Room temperature ferromagnetism has been observed in the nickel-implanted ITO samples with fluences of 1.0 × 10~(17) and 1.5 × 10~(17) ions/cm~2. The magnetic properties of the samples have been explained by the formation of Ni-nanoparticles in the implanted surface layer of the ITO films. Although the formation of a diluted magnetic oxide phase cannot be ruled out entirely, the analysis of our FMR and VSM data reveals that the metallic Ni nanoparticles, formed during high-dose implantation process, have major contribution to the magnetic properties of the Ni-implanted ITO thin films. The sizes of the Ni-nanoparticles have been calculated from the blocking temperatures obtained by the VSM measurements. The filling factor of the Ni ferromagnetic phase in the granular magnetic layer has also been estimated by the effective magnetization approach applied to the FMR results.