Probing and tuning the atomistic antisymmetric exchange interaction at interfaces

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The properties of magnetic solids are governed by the interplay between different microscopic magnetic interactions, i.e., symmetric Heisenberg exchange interaction, antisymmetric Dzyaloshiskii-Moriya interaction (DMI), dipolar interactions, biquadratic interactions, magnetic anisotropy, etc. Owing to its antisymmetric nature, DMI can stabilize topologically protected spin textures, having a unique rotation sense. Examples are spin spirals, spin helixes, skyrmions and antiskyrmions. These are magnetic whirls with a well-defined topological charge. The most important property of theseobjects is that they couple efficiently to spin currents and show a great potential to be used as information storage in future ultrahigh-density, and energy-efficient spin-based logic devices.In this project, we aim to tailor the DMI in magnetic thin films and multilayers. The main objective of the project is twofold. First, we would like to tune the DMI by introducing an additional structural asymmetry in the atomic bilayers made of ferromagnetic materials grown on heavy metal substrates. We will examine different bilayers on W(110) and Ir(111) surfaces. Both the Heisenberg exchange and the DMI will be probed by magnon spectroscopy. Second, we will introduce an additional asymmetry in these systems by adding a monolayer of a heavy metal e.g., Pt on top of these structures and investigate the influence of the additional interface. A complete investigation of all these systems would allow us to understand the fundamental details of the symmetric and antisymmetric magnetic interactions and, in the next step, would enable us to provide guidelines for quantum engineering of these interactions on the atomic length-scales. Such a knowledge is essential to design magnetic multilayers and superlattices, which show specific properties or can host exotic topological spin textures.