08 Fakultät Mathematik und Physik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/9
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Item Open Access Investigating superconductivity by tunneling spectroscopy using oxide heterostructures(2017) Fillis-Tsirakis, Evangelos; Mannhart, Jochen (Prof. Dr.)Item Open Access Exploring the growth of refractory metal and sapphire films by thermal laser epitaxy(2024) Majer, Lena N.; Mannhart, Jochen (Prof. Dr.)Item Open Access From Hermitian to non-Hermitian topological phases of matter(2019) Rui, Wenbin; Metzner, Walter (Prof. Dr.)The focus of this thesis lies on extending the theory of topological phases of matter from the Hermitian to the non-Hermitian regime. This includes not only the extension of conventional concepts such as topological invariants and topological boundary states in the theory of Hermitian topological phases, but also the exploration and characterization of entirely new topological phases unique to non-Hermitian systems.Item Open Access Structure and electronic properties of epitaxial monolayer WSe2(2019) Mohammed, Avaise; Takagi, Hidenori (Prof. Dr.)Item Open Access Polarized neutron reflectometry study of complex magnetism and hydrogen incorporation in thin-film structures(2022) Guasco, Laura; Keimer, Bernhard (Prof. Dr.)In this thesis, we present the study of the structural and magnetic properties of simple metals and complex oxide thin films by means of polarized neutron reflectometry. The nuclear and electronic properties of thin films were modified via two routes, namely via hydrogen incorporation, in the case of niobium systems and complex oxide layers, and via depth modulated hole doping, in the case of manganite heterostructures.Item Open Access Real-space spectroscopy of interacting quasiparticles in exotic semimetals(2022) He, Qingyu; Takagi, Hidenori (Prof. Dr.)Item Open Access High quality graphene for magnetic sensing(2022) Herlinger, Patrick; Smet, Jurgen (Dr.)In this thesis, we investigated the reliable fabrication of high quality graphene and its use as Hall transducer material. Charged impurities and random strain fluctuations were identified as main culprits that deteriorate the electrical properties of graphene devices. It was shown that these extrinsic sources of disorder can be reduced through optimized device processing steps as well as the use of a proper substrate material for graphene such as hexagonal boron nitride (hBN). This insulating material is atomically flat and possesses a very low intrinsic density of charged impurities. By performing Raman spectroscopy and electrical transport measurements, both without and with applied magnetic field, on a large number of different types of graphene devices, it was demonstrated that the encapsulation of graphene between hexagonal boron nitride thin films is the best way to obtain high quality graphene devices. However, even for these hBN-encapsulated devices, we still observed a notable sample-to-sample variation of the electrical properties. Therefore, we developed a post-processing technique that allows us to improve the electrical properties of such devices both significantly and reliably. Since our technique is applied after device fabrication, we could also demonstrate its beneficial effect by comparing one and the same device before and after treatment. We then assessed the application of such high quality graphene as Hall transducer material. The dependencies on and between all relevant operating parameters were explored. This allowed us to develop a deep understanding and empirical model for graphene Hall elements, including the interplay between thermal and 1/f noise in these devices. All key performance indicators for Hall sensors were measured and their typical values reported. For comparable device dimensions, hBN-encapsulated graphene Hall elements were found to have the potential to become a strong competitor to existing materials that are used in today's commercial Hall sensors. Unfortunately, the large-scale fabrication of hBN thin films still remains an unresolved challenge for the industrialization of large area, high quality graphene Hall elements. Also, the Si CMOS integration demands further development. Even though the application of graphene in Hall devices is promising, as shown in this work, this use case alone does likely not justify the significant efforts and investments we expect to be necessary to industrialize the fabrication of high quality graphene devices. Instead, these efforts and costs must be shared by developing a common technology platform for 2D materials that can address several commercially attractive applications where graphene or another 2D material offers superior performance as well. We hope that the insights provided in this work can help to accelerate this process.Item Open Access Probing the electronic structure of new 3D Dirac semimetals(2019) Topp, Andreas; Ast, Christian R. (Dr. habil.)In this thesis, ARPES was used to measure the band structure of novel 3D Dirac semimetals, many of which were previously unknown concerning their electronic structure. The main results were obtained characterizing materials of space group (SG) no. 129 and more specifically ZrSiS and related compounds.Item Open Access Growth and characterization of transition metal oxide heterostructures with a tailored work function(2018) Rastegar Alam, Iman; Mannhart, Jochen (Prof. Dr.)Item Open Access X-ray and Raman scattering studies of novel phases in 3d and 4d transition metal oxides(2020) Fürsich, Katrin; Keimer, Bernhard (Prof. Dr.)