Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 56: Poster Session: Low-Dimensional Systems

TT 56.2: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P2-OG4

Photoemission study of the bulk band dispersion in 1T-TaS₂ at 30 K — •Arlette S. Ngankeu¹, Sanjoy K. Mahatha¹, Marco Bianchi¹, Charlotte E. Sanders¹, Kai Rossnagel², and Philip Hofmann¹ — ¹Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark — ²Institute for Experimental and Applied Physics, University of Kiel, 24098 Kiel, Germany

The ground states of many layered transition metal dichalcogenides, including 1T-TaS₂, are governed by charge density waves (CDWs) associated with periodic lattice distortions. These distortions are accompanied by changes of the electronic structure due to Brillouin zone reconstructions. In the case of 1T-TaS₂, the low-temperature commensurate CDW state even coexists with a Mott-insulating ground state. While many studies have addressed the origin of the CDW in 1T-TaS₂, there have been recent theoretical results specifically addressing the three-dimensional nature of the bands associated with the Mott state, finding that the Mott state leads to an insulating in-plane state while the out-of-plane dispersion of the state remains metallic.

We have investigated the electronic band structure of 1T-TaS₂ in the commensurate-CDW phase in all three dimensions by means of synchrotron radiation-based angle resolved photoemission spectroscopy. The measured in-plane band structure is consistent with previous results from the literature. We observe an out-of-plane dispersion of the lower Mott state, as predicted, but no Fermi crossing, such that a 3D insulating behavior is retained.