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Title:Dissecting Mott and charge-density wave dynamics in the photoinduced phase of 1T-TaS[sub]2
Authors:Simoncig, Alberto (Author)
Stupar, Matija (Author)
Ressel, Barbara (Author)
Saha, Tanusree (Author)
Rebernik Ribič, Primož (Author)
De Ninno, Giovanni (Author)
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Work type:Unknown ()
Tipology:1.01 - Original Scientific Article
Organization:UNG - University of Nova Gorica
Abstract:The two-dimensional transition-metal dichalcogenide 1T−TaS2 is a complex material standing out for its puzzling low temperature phase marked by signatures amenable to both Mott-insulating and charge-density wave states. Electronic Mott states, coupled to a lattice, respond to coherent optical excitations via a modulation of the lower (valence) Hubbard band. Such dynamics is driven by strong electron-phonon coupling and typically lasts for tens of picoseconds, mimicking coherent structural distortions. Instead, the response occurring at the much faster timescale, mainly dominated by electronic many-body effects, is still a matter of intense research. By performing time- and angle-resolved photoemission spectroscopy, we investigated the photoinduced phase of 1T−TaS2 and found out that its lower Hubbard band promptly reacts to coherent optical excitations by shifting its binding energy towards a slightly larger value. This process lasts for a time comparable to the optical pump pulse length, mirroring a transient change of the onsite Coulomb repulsion energy (U). Such an observation suggests that the correction to the bare value of U, ascribed to the phonon-mediated screening which slightly opposes the Hubbard repulsion, is lost within an interval of a few tens of femtoseconds and can be understood as a fingerprint of electronic states largely decoupled from the lattice. Additionally, these results enforce the hypothesis, envisaged in the current literature, that the transient photoinduced states belong to a sort of crossover phase instead of an equilibrium metallic one.
Keywords:ultrafast phenomena, time resolved photoemission, strongly correlated systems, transition metal dichalcogenide
Year of publishing:2021
Number of pages:str. 1-7
Numbering:iss. 5, Vol. 103
COBISS_ID:59328771 Link is opened in a new window
ISSN on article:2469-9950
DOI:10.1103/PhysRevB.103.155120 Link is opened in a new window
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Title:Physical review
Publisher:American Physical Society
COBISS.SI-ID:2997348 New window