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| Hauptseite > Publikationsdatenbank > Spin-orbital mixing in the topological ladder of the two-dimensional metal PtTe2 |
| Hauptseite > Publikationsdatenbank > Spin-orbital mixing in the topological ladder of the two-dimensional metal PtTe2 |
| Book/Dissertation / PhD Thesis | FZJ-2025-05733 |
2025
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-872-8
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Please use a persistent id in citations: doi:10.34734/FZJ-2025-05733
Abstract: Spin polarization is a fundamental concept in condensed matter physics, with key implications for theory and spintronics. Unlike charge-based electronics, spintronics exploits electrons’ intrinsic spin, enabling faster and more energy-efficient information processing. However, accurately characterizing intrinsic spin properties is challenging due to interactions between initial electronic states and final-state effects during experimental measurements. This thesis addresses these challenges using advanced high-resolution spin- and angle-resolved photoelectron spectroscopy (spin-ARPES), a powerful technique that provides comprehensive two-dimensional mapping of spin textures, allowing for a more accurate assessment of intrinsic spin characteristics across electronic states. This research focuses on PtTe2, a type-II Dirac semimetal with topological surface states that collectively form a so-called topological ladder. By visualizing its spin textures, we highlight the nature of its spin polarization. PtTe2 has exceptional properties, such as the highest room-temperature electrical conductivity among metallic transition metal dichalcogenides. Its high spin-orbit torque efficiency also leads to substantial spin Hall conductivity in thin films, making it well-suited for wafer-scale spintronic applications. Various experimental geometries were employed to evaluate how surface symmetries and light incidence angles influence spin polarization. When light impinges on the sample within a mirror plane, symmetric spin-polarized maps align with corresponding initial-state calculations. Conversely, asymmetries emerge in measured spin textures of surface and bulk states when a mirror plane is absent, deviating from initial-state predictions. Some observed asymmetries arise from the intrinsic asymmetric bulk crystal structure, accessible through the surface sensitivity of spin-ARPES, particularly within the hidden spin-polarization phenomenon. Others stem from geometryrelated factors, where the absence of a relevant mirror plane introduces phase shifts in the photoemission matrix element, leading to these asymmetries. Additionally, calculations reveal that spin-orbit coupling (SOC) scattering-induced spin polarization accounts for up to 15% of the total observed 50% polarization in PtTe2, that is revealed based on the adapted experimental geometry. Furthermore, findings extend to the related compound PdTe2, where similar behaviors reinforce the applicability of the developed methodologies. By addressing ambiguities in spin texture observations, this research provides critical insights into the nature of spin polarization and its implications for the efficient design of spinbased devices. Ultimately, this thesis enhances the fundamental understanding of intrinsic spin properties in SOC materials, paving the way for their integration into next-generation spintronic technologies.
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