Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Surface Dynamics II
O 89.5: Vortrag
Freitag, 15. März 2013, 11:30–11:45, H33
Femtosecond time-resolved photoemission on 1T-TaS2 in the Mott-insulating state — •Isabella Avigo1, Simon Freutel1, Laurenz Rettig1, Manuel Ligges1, Lutz Kipp2, Kai Rossnagel2, and Uwe Bovensiepen1 — 1(1)*Universität Duisburg-Essen, D 47048 Duisburg — 2(2)*Christian-Albrechts-Universität zu Kiel, D 24118 Kiel
1T-TaS2 is a quasi-two-dimensional transition metal dichalcogenide undergoing a metal-to-insulator transition below 180 K in which a charge density wave (CDW) coexists with a Mott insulating state. Of particular interest is the photoinduced melting of the Mott-Hubbard phase which drives the system in a crossover state [1,2] substantially different from the high temperature metallic state. Femtosecond time- and angle-resolved photoemission measurements were performed in the Mott-insulating phase at different pump fluences from 0.1 to 1 mJ/cm2. We observe a population of states above the Fermi level (EF) after pumping and a depletion and broadening of the lower Hubbard band (LHB) peak below EF. Our analysis reveals a difference in the relaxation dynamics of the electron population above EF, which decays in about 350 fs, and the intensity of the lower Hubbard band, recovering in about 900 fs. This points to a possible decoupling of populations above and below EF and thus to an at least unconventional metallic behavior in the photoinduced state.
We acknowledge support by the DFG through BO 1823/2, /4 and the EU under grant agreement 280555 within FP7. [1] Perfetti et al., NJP 10, 053019 (2008) [2] Dean et al., PRL 106, 016401 (2011)