SKM 2021 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 2: Focus Session: Exotic Charge Density Wave States of Matter: Correlations and Topology (joint session TT/HL)

HL 2.2: Vortrag

Montag, 27. September 2021, 10:30–11:00, H7

Non-local electronic correlations in 1T-TaS₂ out of equilibrium — •Uwe Bovensiepen — University of Duisburg-Essen, Faculty of Physics and Center for Nanointegration (CENIDE), 47048 Duisburg, Germany

Transition metal dichalcogenides with a d¹ transition metal electron configuration exhibit broken symmetry ground states and distorted structures. The formation of charge density wave (CDW) states in conjunction with Mott physics in 1T-TaS₂ is a well know example. Current efforts aim at microscopic understanding of the intertwined electronic and lattice effects. In this regard experiments in the time domain provide direct insights because the characteristically different timescales of electronic hopping with a time constant ℏ /J≈2 fs and the CDW amplitude period of 400 fs can be well distinguished. In this talk time-resolved photoelectron spectroscopy results will be presented in connection with theoretical results to discuss electronic excitations and their dynamics. Excitation and relaxation of doubly occupied sites is mediated by intersite hopping and coupling to delocalized electrons [1,2]. Comparison with literature indicates that such electron dynamics can be excited selectively, separate from lattice excitations. First experiments towards bulk sensitive, time-resolved photoelectron spectroscopy [3] will be discussed as well.
Funding by the DFG through SFB 1242 is gratefully acknowledged. [1] Ligges et al., PRL 120, 166401 (2018)
[2] Avigo et al., PR Research 2, 022046(R) (2020)
[3] Beyazit et al., PRL 125, 076803 (2020)