SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 18: Poster: 2D Materials I
O 18.5: Poster
Monday, March 27, 2023, 18:00–20:00, P2/EG
Unoccupied electronic states of the CDW material 1T-TiSe2 — •Patrick Geers, Marcel Holtmann, and Markus Donath — Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster
We present angle-resolved inverse-photoemission (IPE) measurements of the unoccupied electronic structure of the transition metal dichalcogenide 1T-TiSe2. The spectra along the Γ M and Γ K high symmetry directions are dominated by the Ti-3d bands with rather flat E(k∥) dispersion. The two energetically separated subgroups eg and t2g are clearly resolved in the spectra. We observe two eg bands as expected, while the spectral features of the t2g group are too broad to identify the three predicted states individually. In addition, an image-potential surface state with its free-electron-like dispersion is observed below the vacuum energy. We compare our experimental E(k∥) results with a theoretical 3D bandstructure by estimating the k⊥-component of the electron wavevector within the nearly-free-electron approximation. Furthermore, we observe temperature-dependent changes in our IPE data that are attributed to the charge density wave phase transition. Interestingly, only bands of t2g symmetry show energy shifts, proving the orbital selectivity of bands involved in the phase transition [1].
[1] Watson et al., Phys. Rev. Lett. 122, 076404 (2019).