Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Organic films and electronics, photoorganics; Nanostructures; Plasmonics and nanooptics, Surface chemical reactions and heterogeneous catalysis, Surface dynamics )
O 36.65: Poster
Dienstag, 12. März 2013, 18:15–21:45, Poster B2
Are there coherent phonon signatures of a photoinduced, meta-stable state in 1T-TaS2? — •Manuel Ligges1, Simon Freutel1, Isabella Avigo1, Ljupka Stojchevska3, Laurenz Rettig1, Tomaz Mertelj3, Ping Zhou1, Dragan Mihailovic3,4, Lutz Kipp2, Kai Rossnagel2, and Uwe Bovensiepen1 — 1Univ. Duisburg-Essen, Germany — 2Christian-Albrechts-Univ. zu Kiel, Germany — 3Complex Matter Dept., Jozef Stefan Institute, Ljubljana, Slovenia — 4CENN Nanocentre, Ljubljana, Slovenia
1T-TaS2 is a layered transition metal-dichalgoenide that exhibits a manifold of electronic and structural phases, giving rise to a complex interplay between electronic correlation effects and structural modifications. Of particular interest is the photo-induced melting of the Mott-Hubbard phase that is associated with a partial removal of commensurate charge-density wave (CCDW) order. We performed pump-probe photoemission experiments in which coherent phonon signatures associated with the amplitude mode of this CCDW are observed. Upon strong (a few mJ/cm2) infrared few-pulse pre-excitation of the material before the pump-probe experiments, severe changes in the vibrational spectrum can be observed that persist on very long timescales (> hrs). The signature observed before this intense excitation (2.4 THz) splits up into a 2.4 THz and a 2.5 THz component with comparable amplitude. We will discuss meta-stable configurations of the CCDW ordered state as a potential origin of this observation. We acknowledge financial support by the Deutsche Forschungsgemeinschaft through BO 1823/2, /4 and the European Union under grant agreement 280555 within FP7.