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Dissertation
Validation of a generalized model for the description of polycrystalline exchange-biased magnetic thin films
(2022)
Applications based on nano- and microscaled systems have become indispensable in many aspects in everyday life, industry, research and medicine. In this regard, thin film technology plays a crucial role with the physical properties of solids changing significantly when they are reduced to thin layers with thicknesses in the nanometer range. In this regime, a solid’s microstructure as well as boundary and surface effects start to dominate. A prominent example is the exchange bias effect, which results due to the ...
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Three-electron radiative transitions
(1993)
A new type of many-electron radiative transitions involving three electrons is predicted. The results of their investigation by many-body perturbation theory are presented. New spectral lines observed in the wavelength range of 37.5 to 54.0 nm by means of photon-induced fluorescence spectroscopy (PIFS) following the excitation of the Kr I 3d{^-1}np resonances are reported and compared with the predictions.
Dissertation
Interatomic Coulombic decay in noble gas clusters of varying sizes investigated by photon-induced (dispersed) fluorescence spectrometry
(2018-06-06)
The main topic of this thesis is to study experimentally an ultrafast and efficient non radiative mechanism – the well-known interatomic Coulombic decay (ICD) – in noble gas clusters by employing fluorescence spectrometry technique in combination with synchrotron radiation. Using Neon clusters as prototype systems, a special variety of ICD, termed resonant ICD (RICD), has been investigated by a selective excitation of one component of the cluster and for different mean cluster sizes. The first part of the thesis was ...
Dissertation
Domänenwandwiderstandseffekt in künstlich erstellten Domänenwänden nach Ionenbeschuss von magnetischen Zweischichtsystemen
(2014-02-25)
Im Rahmen dieser Arbeit wurden magnetische Zweischichtsysteme mit Exchange-Bias-Effekt und künstlichen lateralen Domänenstrukturen auf den Domänenwandwiderstand (DWR) untersucht. Die Erzeugung dieser Domänenmuster erfolgte über Ion Bombardment induced Magnetic Patterning (IBMP), d.h. 10 keV Helium-Ionenbeschuss durch Schattenmasken auf der Probenoberfläche. Mithilfe eines externen Magnetfelds können anschließend die Domänenwände gezielt ein- und ausgeschaltet werden. Zur Untersuchung des DWR-Effekts müssen einige ...
Dissertation
Visualizing the electronic structure of small molecules with rovibronic photon emission spectroscopy
(2018)
A key in understanding the fundamental structure of atoms and molecules has been their absorption and emission of electromagnetic radiation across all spectral ranges. The observation of discrete line spectra contributed to the development of core concepts in quantum mechanics and thus the modern picture of physical processes occurring at small scales. The ongoing refinement of both experimental and theoretical methods in spectroscopy allows to deal with succeedingly more complex systems in different interactions to ...
Dissertation
Asymmetric magnetization reversal processes in exchange-biased microstructures
(2023)
Over the last decades, the exchange bias (EB) effect has captured the attention of the research community striving for high-density logic memory devices and sensitive sensor technologies based on bi-, multilayered, or patterned magnetic thin film systems. Macroscopically, the EB manifests in a horizontal shift of the ferromagnetic remagnetization loop and an enhancement of the coercivity, both connected to the induced unidirectional anisotropy (UDA) at the exchange-coupled ferromagnetic/antiferromagnetic interface. ...
Dissertation
Towards the investigation of ultrafast dynamics in chiral systems using free-electron lasers
(2024)
Chiral molecules are life’s building blocks, making the study of their ultrafast processes a pursuit across various fundamental research fields. The results presented in this dissertation contain methodological, technical and scientific advancements that pave the way for future time-resolved, site-specific investigations into chiral photochemistry of randomly orientated molecules, using photoelectron circular dichroism and free-electron lasers. The high-repetitionrate free-electron lasers EuXFEL and FLASH2 will soon ...