20.500.12556/RUNG-6471
Dissecting Mott and charge-density wave dynamics in the photoinduced phase of 1T-TaS[sub]2
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.
ultrafast phenomena
time resolved photoemission
strongly correlated systems
transition metal dichalcogenide
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Angleški jezik
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2021-04-13 10:10:48
2021-04-13 10:30:28
2023-06-09 03:43:21
0000-00-00 00:00:00
2021
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0
str. 1-7
iss. 5
Vol. 103
Apr. 2021
0000-00-00
NiDoloceno
NiDoloceno
NiDoloceno
0000-00-00
0000-00-00
0000-00-00
59328771
53
2469-9950
10.1103/PhysRevB.103.155120
URN:SI:UNG:REP:OCCSHWAX
Univerza v Novi Gorici
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