Alberto Simoncig (Avtor), Matija Stupar (Avtor), Barbara Ressel (Avtor), Tanusree Saha (Avtor), Primož Rebernik Ribič (Avtor), Giovanni De Ninno (Avtor)

Povzetek

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.

Ključne besede

ultrafast phenomena;time resolved photoemission;strongly correlated systems;transition metal dichalcogenide;

Podatki

Jezik: Angleški jezik
Leto izida:
Tipologija: 1.01 - Izvirni znanstveni članek
Organizacija: UNG - Univerza v Novi Gorici
UDK: 53
COBISS: 59328771 Povezava se bo odprla v novem oknu
ISSN: 2469-9950
Št. ogledov: 1624
Št. prenosov: 0
Ocena: 0 (0 glasov)
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Ostali podatki

URN: URN:SI:UNG
Strani: str. 1-7
Letnik: ǂVol. ǂ103
Zvezek: ǂiss. ǂ5
Čas izdaje: Apr. 2021
DOI: 10.1103/PhysRevB.103.155120
ID: 12765908