Regensburg 2025 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 54: Correlated Electrons: Charge Order
TT 54.5: Vortrag
Freitag, 21. März 2025, 10:30–10:45, H33
Tunable Charge Density Wave Orders in 2H-TaS2 — •Mihir Date1,2, Joost Aretz3, Enrico da Como4, Marcin Mucha-Kruczynski4, Malte Roesner3, Stuart S P Parkin1, Niels B M Schroeter1, and Matthew D Watson2 — 1Max Planck Institute of Microstructure Physics, Halle, Germany — 2Diamond Light Source Ltd., Didcot, UK — 3Radboud University, Nijmegen, The Netherlands — 4University of Bath, Bath, UK
The charge density wave (CDW) transition is an electronic instability driven by strong electron-phonon coupling, where the parent electronic band is renormalized, and shows a spectral gap. Angle-resolved photoemission spectroscopy (ARPES) has been extremely successful in identifying these spectral features, most prominently in layered van der Waals materials like 2H-NbSe2 and TaSe2. Surprisingly, however, until now there has not been any high-quality data reported on the 2H-TaS2, presumably due to materials challenges. Making use of spatially resolved ARPES, we were able to overcome these challenges and measure high-quality bandstructures revealing the 3x3 commensurate charge density waves (CCDW) ground state in 2H-TaS2. We further find variation of the stoichiometry between samples prepared by different routes, and incredibly, at a different band filling we find evidence of a new CDW order that is commensurate, but not the 3x3 reconstruction as observed in previous experiments. Our results are compared with tight-binding and ab-initio modelling which show that TaS2 is prone to multiple instabilities that can be tuned by the band filling, with an important role played by a van Hove singularity.
Keywords: Charge density waves; TaS2; ARPES; van Hove singularity; Electron-phonon coupling