Fabrication of Au, Ag, Pd and Ho doped Y3Fe5O12 thin films and investigation of their magnetic and optical properties

In this study, undoped, holmium (Ho), silver (Ag), palladium (Pd) and gold (Au) doped yttrium iron garnet (YIG) thin films were successfully synthesized on thermally oxidized silicon (Si) substrates by sol-gel method. In order to observe the difference between direct doping and nanoparticle doping of noble metals (Ag, Au and Pd), both direct doping and nanoparticle forms produced by the polyol method were doped in the same proportions. The structural, magnetic and optical properties of the undoped and doped YIG thin films were investigated. XRD analysis of all films exhibited characteristic YIG diffraction peaks and XRD patterns confirmed that the YIG films crystallized in a single phase cubic garnet structure. SEM images of all films confirmed that the optimized heat treatment results by two-step annealing were successful in obtaining smooth thin films without cracks and nucleation. From the magnetic field dependent magnetization (M-H) measurements of the samples, it was observed that the saturation magnetization values of all samples at room temperature increased after doping and this value increased up to about 8 times in Pd doped samples and up to 11 times in Au doped samples. In ferromagnetic resonance (FMR) measurements, it was observed that the FMR line widths of the films were considerably lower than the YIG thin films produced by the same method in the literature. According to the data obtained from optical measurements, it has been revealed that the absorption coefficients of thin films vary according to the doping material, but doping independent of the doping material has an improving effect on both magnetic and optical properties of thin films. Noble metal doped YIG thin films produced within the scope of this thesis have been studied for the first time in the literature. The experimental data obtained show that the surface plasmonic resonance effect of noble metals significantly improves the magnetic properties of YIG thin films. For this reason, it is thought that the data obtained within the scope of the thesis will lead to further studies on the effect of surface plasmonic resonance effect on the magnetic properties of materials. Keywords: YIG, noble metals, magneto-optical materials, sol-gel method