Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 65: Time-resolved spectroscopies III

O 65.5: Vortrag

Freitag, 27. März 2009, 12:15–12:30, SCH A315

Ultrafast dynamics in the 1T-TiSe₂ transition-metal dichalcogenide in the vicinity of the CDW phase transition — •Martin Wiesenmayer¹, Stephan Hilgenfeldt¹, Stefan Mathias², Timm Rohwer¹, and Michael Bauer¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany — ²Department of Physics, TU Kaiserslautern, 67663 Kaiserslautern, Germany

The layered transition metal dichalcogenides (TMDC) have attracted considerable attention in the past due to a wide range of phenomena associated with their reduced dimensionality, such as charge density wave (CDW) instabilities and enhanced correlation effects. In this paper we report on a two-photon photoemission study of the TMDC compound 1T-TiSe₂. Static 2PPE measurements reveal a strong quenching of the signal of the occupied Se 4p bands as the incident laser intensity increases. We find that the characteristic timescales associated with this quenching lie in the femtosecond to picosecond range, indicating the involvement and relevance of electronic excitations. Furthermore, the experiments show clear differences in the quenching behavior between the normal and the CDW state of 1T-TiSe₂. Our results will be discussed under consideration of the highly disputed mechanism for the CDW transition of this compound.