Probing charge density wave phases and the Mott transition in 1TTaS2 by inelastic light scattering

S. Djurdjić Mijin, A. Baum, J. Bekaert, A. Šolajić, J. Pešić, Y. Liu, Ge He, M. V. Milošević, C. Petrovic, Z. V. Popović, R. Hackl, and N. Lazarević
Phys. Rev. B 103, 245133 – Published 22 June 2021

Abstract

We present a polarization-resolved, high-resolution Raman scattering study of the three consecutive charge density wave (CDW) regimes in 1TTaS2 single crystals, supported by ab initio calculations. Our analysis of the spectra within the low-temperature commensurate (C-CDW) regime shows P3¯ symmetry of the system, thus excluding the previously proposed triclinic stacking of the “star-of-David” structure, and promoting trigonal or hexagonal stacking instead. The spectra of the high-temperature incommensurate (IC-CDW) phase directly project the phonon density of states due to the breaking of the translational invariance, supplemented by sizable electron-phonon coupling. Between 200 and 352 K, our Raman spectra show contributions from both the IC-CDW and the C-CDW phases, indicating their coexistence in the so-called nearly commensurate (NC-CDW) phase. The temperature dependence of the symmetry-resolved Raman conductivity indicates the stepwise reduction of the density of states in the CDW phases, followed by a Mott transition within the C-CDW phase. We determine the size of the Mott gap to be Ωgap170190 meV, and track its temperature dependence.

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  • Received 10 March 2021
  • Revised 14 June 2021
  • Accepted 16 June 2021

DOI:https://doi.org/10.1103/PhysRevB.103.245133

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

S. Djurdjić Mijin1, A. Baum2, J. Bekaert3, A. Šolajić1, J. Pešić1, Y. Liu4,*, Ge He2, M. V. Milošević3, C. Petrovic4, Z. V. Popović1,5, R. Hackl2, and N. Lazarević1

  • 1Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, RS-11080 Belgrade, Serbia
  • 2Walther Meissner Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
  • 3Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
  • 4Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
  • 5Serbian Academy of Sciences and Arts, Knez Mihailova 35, RS-11000 Belgrade, Serbia

  • *Present address: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

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Issue

Vol. 103, Iss. 24 — 15 June 2021

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