Eintrag in der Universitätsbibliographie der TU Chemnitz
Volltext zugänglich unter
URN: urn:nbn:de:bsz:ch1-qucosa2-975237
Kulmus, Kathrin
Schreiber, Michael (Prof. Dr.) ; Gemming, Sibylle (Prof. Dr.) (Gutachter)
Theoretical investigations on the electronic properties of VO2 and NbO2
Kurzfassung in englisch
The transition metal dioxide NbO2 changes its phase from a semi-conducting low-temperature body-centered tetragonal to a metallic high-temperature rutile structure at the critical temperature, which is around 1080 K. This transition can also be triggered by photoexcitation. The aim of this thesis is to examine the physical nature of NbO2 . For this purpose elaborate simulations on quantum mechanical all-electron level are performed and physically interpreted. By systematically reducing the amount of simplification in the simulation, we obtain new insights about the physics of NbO2 . Consequently the first part of this work is dedicated to the theoretical foundation of our method. The attention is turned to the capability of explaining the experimental findings. To validate our approach it is first applied to the higher homolog VO2 , which is experimentally and theoretically investigated more intensely. In agreement with previous studies, we find that the insulator-to-metal transition is merely triggered electronically. Further considerations on photoexcitation experiments show that the laser pulses do not trigger the phase transition, but lead to an unbalanced state, which is not stable. After this thoroughly examined validation, we apply the method to NbO2 . We find that the physical nature of it is best described within the Peierls theory. Unlike most other studies, which focus primarily on the insulating phase, we also focus on the metallic state and give a comprehensive description of the physics of NbO2 which includes both of its solid state phases.
| Universität: | Technische Universität Chemnitz | |
| Institut: | Professur Theoretische Physik (-Theorie ungeordneter Systeme-) | |
| Fakultät: | Fakultät für Naturwissenschaften | |
| Dokumentart: | Dissertation | |
| Betreuer: | Schreiber, Michael (Prof. Dr.) | |
| DOI: | doi:10.60687/2025-0120 | |
| SWD-Schlagwörter: | Elektronenstruktur , Simulation , Metall-Isolator-Phasenumwandlung , Bethe-Salpeter-Gleichung , Dielektrische Funktion , Peierls-Übergang | |
| Freie Schlagwörter (Englisch): | NbO2 , VO2 , electronic properties , dielectric function , Fermi surface , Peierls transition , Hedin’s equations , Bethe-Salpeter equation , all-electron calculations , Questaal | |
| DDC-Sachgruppe: | Physik | |
| Sprache: | englisch | |
| Tag der mündlichen Prüfung | 19.05.2025 | |
| OA-Lizenz | CC BY 4.0 |
