Tuning magnetic properties in nanostructures on different length scales

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The aim of the project is the experimental and theoretical investigation of the possibility to tune magnetic properties of nanostructures via modification of interface roughness at different length scales which can be achieved by variation of growth regimes, self-organization of chemical and magnetic clusters during annealing or remagnetization process, formation of artificial lateral structures, hydrogen absorption and other external actions. We will investigate the onset of magnetic behavior in submonolayer overlayers on metal surface. Spin resolved study of quantum well states will allow us to investigate magnetic features with atomic resolution. For Heusler alloys we will trace how annealing induced self-organization in amorphous films can lead to the formation of long-range order and revive the magnetic response of the system. In magnetic nanostructures with V spacer layers we will investigate the influence of reversible hydrogen adsorption on the evolution of non-collinear magnetic ordering for already grown samples. Thus, tuning the magnetic properties will be studied at different spatial scales within a single approach. Advanced technologies for nanostructure growth and electron beam lithography will be used which are available at the Universities participating in the project. Special treatment of substrate and buffer layers, changing of temperature regime, deposition ratio during the growth, other special inventions, such as hydrogen assisted growth, will allow to make nanostructures with required interface structure. Than complimentary experimental methods with using of large scale facilities at BESSY and ILL will be applied for sample control as well as for the investigation of structural and magnetic properties. The theoretical description will include modelling of the epitaxial growth with self-consistent calculations of electronic and magnetic structures on the basis of ab initio and model Hamiltonian approaches. Original codes developed by project participants will be used for calculation of complex, spatially non-homogeneous structures taking into account possible non-collinear magnetic ordering in external local magnetic fields. The aim is to provide the first atomic scale calculations of remagnetization processes in nanostructures within a microscopic Hamiltonian approach for itinerant electrons. The project will thus enable the collaborating project team to use advanced material technology and theoretical approaches for addressing fundamental questions about interface roughness, magnetism and their evolution under external actions.