Tailoring Properties of Materials at the Nanoscale

Abstract: The knowledge of growth and characterizing techniques is essential for the preparation of high quality thin films and multilayers. Here, structural properties have been investigated by X-ray reflectivity, X-ray diffraction, and transmission electron microscopy while the composition was determined by Rutherford backscattering spectrometry. For the magnetic studies, magneto-optical Kerr effect and X-ray magnetic circular dichroism have been used.The structural properties of the metal/insulator multilayer system, Fe/MgO, have been investigated. The coherency of the layers was influenced by the difference of the atomic distance in the Fe and MgO layers, resulting in long range strain fields. As a consequence, the coherency between the layers is not maintained.The atomic steps can not exist in amorphous materials, due to the absence of well defined atomic distances. Furthermore, the magnetic properties of amorphous materials allow a tuning of magnetic properties such as magnetic anisotropy and ordering temperature. The possibility to imprint arbitrary magnetic anisotropy in nanolaminated magnetic amorphous Co68Fe24Zr8 was demonstrated. The ratio of the orbital to spin moments for both Fe and Co was determined, for both thick and thin layers embedded in amorphous Al70Zr30 layers. When growing Co68Fe24Zr8 /Al2O3 the layers exhibit large changes in layer quality with thickness of the layers, ultimately affecting the magnetic properties of the stack.The use of protective layers is of large importance when performing ex-situ measurements. Most of the materials used were capped by Al2O3, effectively hindering both the reaction with oxygen and water. The penetration of hydrogen through different thicknesses of alumina was investigated. The experiments confirmed high degree of passivation as well as the possibility to selectively diffuse hydrogen through these layers. The use of element specific diffusion barriers allows the tailoring of magnetic properties of magnetic thin films and multilayers.