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: |
2021 |
Tipologija: |
1.01 - Izvirni znanstveni članek |
Organizacija: |
UNG - Univerza v Novi Gorici |
UDK: |
53 |
COBISS: |
59328771
|
ISSN: |
2469-9950 |
Št. ogledov: |
1624 |
Št. prenosov: |
0 |
Ocena: |
0 (0 glasov) |
Metapodatki: |
|
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 |