SKM 2023 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 40: 2D Materials V: Growth, Structure and Substrate Interaction (joint session O/CPP)
CPP 40.2: Vortrag
Mittwoch, 29. März 2023, 15:15–15:30, GER 37
Electronic, chemical and structural properties of ultrathin Ta2NiSe5 flakes — •Kathrin Küster1, Yuanshan Zhang1, Dennis Huang1, Ulrich Starke1, and Hidenori Takagi1,2,3 — 1Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany — 2Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569 Stuttgart, Germany — 3Department of Physics, University of Tokyo, 113-0033 Tokyo, Japan
The excitonic insulator is a theoretically proposed state of matter wherein a macroscopic condensate of electron-hole pairs, i.e., excitons, spontaneously forms below a transition temperature. The 2D-layered chalcogenide Ta2NiSe5 has arisen as a leading candidate of an excitonic insulator in a bulk crystal. Here we prepared ultrathin films (down to 2 nm) of Ta2NiSe5 and analyzed their structural, electronic and chemical properties with a NanoESCA (Scienta Omicron) on a local scale. Angle-resolved photoelectron spectroscopy (ARPES), X-ray photoelectron spectroscopy (XPS), together with photoelectron emission microscopy (PEEM) and imaging XPS give detailed insight into the thickness dependent properties of the flakes. By exposure to UV-light we observe a contrast change in the PEEM images which is caused by a strong modification of the work function of the flakes, which we tentatively relate to a phase transition of the Ta2NiSe5 flakes.