Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 48: 2D Materials 1: Electronic Structure of Transition Metal Dichalcogenides
O 48.5: Vortrag
Mittwoch, 7. September 2022, 16:00–16:15, S052
Unoccupied electronic states of 1T-TiSe2: Band dispersions and CDW-induced changes at Γ — •Patrick Geers, Marcel Holtmann, and Markus Donath — University of Münster, Germany
The transition metal dichalcogenide 1T-TiSe2 shows a phase transition into a charge density wave (CDW) below a critical temperature TCDW [1]. This transition leads to a half-sized Brillouin zone and backfolded electronic bands. For the occupied electronic structure, photoemission results show a backfolding of Se-4px,y valence bands below TCDW from Γ to M [2].
We present angle-resolved inverse-photoemission (IPE) measurements for the unoccupied electronic structure above and below TCDW. Our data for the Γ M azimuth resemble literature data for the energy vs. momentum dispersion of Ti-3d states as well as an image-potential-induced surface state [3]. In addition, we report on IPE measurements for the Γ K azimuth. Finally, we give special attention to the changes in the electronic structure, which are caused by the CDW phase transition. Measurements around Γ below TCDW show modifications in the spectra which are attributed to backfolded electronic bands from M to Γ as a direct consequence of the CDW phase.
[1] Di Salvo et al., Phys. Rev. B 14, 4321 (1976).
[2] Watson et al., Phys. Rev. Lett. 122, 076404 (2019).
[3] Drube et al., J. Phys. C 20, 4201 (1987).