Bulletin of the American Physical Society
2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session D20: Non-Carbon 2D materials I
3:00 PM–6:00 PM,
Monday, March 6, 2023
Room: Room 212
Sponsoring
Unit:
DCMP
Chair: Matthew Enjalran, Southern Connecticut State University
Abstract: D20.00012 : Heterogeneous Ta-dichalcogenides bilayer: heavy fermions or doped Mott physics?*
5:12 PM–5:24 PM
Presenter:
Roser Valenti
(Goethe University Frankfurt)
Authors:
Roser Valenti
(Goethe University Frankfurt)
Igor I Mazin
(George Mason University)
Paul Wunderlich
(Goethe University Frankfurt)
Giorgio Sangiovanni
(Julius-Maximilians University of Wuerzbu)
Tim Wehling
(University of Hamburg)
Recently, a series of intriguing experiments have been reported on 1H/1T bilayers of TaCh2 (Ch=S,Se), where tunneling from the 1H surface shows metallic spectra similar to bulk 2H-TaCh2, while the 1T surface shows a strong central peak, sometimes with satellites, as opposed to a well-defined Mott-Hubbard gap in pure 1T-TaCh2. In these reports, the effect was interpreted as a Kondo-type hybridization between the localized spins in 1T layers and itinerant electrons in 1H layers, implying a heavy-fermion nature of the observed peak. We have calculated the electronic structure of such bilayers, and found that even at large separation there is a sizeable charge transfer (0.4-0.6 e) from 1T to 1H. We performed Dynamical Mean Field Theory (DMFT) calculations including this charge transfer, the 1T-1H hybridization and the Mott charge density wave in 1T and find that we reproduce the experiments rather well, but, contrary to previous assumptions, the role of hybridization-induced Kondo screening is negligible, although the screening enabled by the mobile holes in the 2T layer was critical. We point out that this intriguing system is closer to a doped Mott insulator than a heavy-fermion system.
*IIM was supported by ONR (N00014-20-1-2345)GS, TW and RV acknowledge support from the Deutsche Forschungsgemeinschaft (DFG, German Science Foundation) through FOR 5249-449872909 "QUAST"
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