Journal Article

PUBDB-2024-00348

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Electronic structure and lattice dynamics of $1 T − VSe_2$ : Origin of the three-dimensional charge density wave

Diego, J. (Corresponding author) ; Subires, D. (Corresponding author) ; Said, A. ; Chaney, D. A. ; Korshunov, A.Extern* ; Garbarino, G. ; Diekmann, F. ; Mahatha, S. K. ; Pardo, V. ; Wilkinson, J. M. ; Lord, J. S. ; Strempfer, J. ; Bereciartua Perez, P. J.DESY* ; Francoual, S.DESY* ; Popescu, C. ; Tallarida, M. ; Dai, J. ; Bianco, R. ; Monacelli, L. ; Calandra, M. ; BOSAK, A. ; Mauri, F. ; Rossnagel, K.DESY* ; Fumega, A. O. ; Errea, I. (Corresponding author) ; Blanco-Canosa, S. (Corresponding author)

2024
Inst. Woodbury, NY

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Please use a persistent id in citations: doi:10.1103/PhysRevB.109.035133  doi:10.3204/PUBDB-2024-00348

Abstract: To characterize in detail the charge density wave (CDW) transition of $1 T − VSe_2$, its electronic structure and lattice dynamics are comprehensively studied by means of x-ray diffraction, muon spectroscopy, angle resolved photoemission (ARPES), diffuse and inelastic x-ray scattering, and state-of-the-art first-principles density functional theory calculations. Resonant elastic x-ray scattering does not show any resonant enhancement at either V or Se, indicating that the CDW peak at the K edges describes a purely structural modulation of the electronic ordering. ARPES experiments identify (i) a pseudogap at $T>T_{CDW}$, which leads to a depletion of the density of states in the ML-M'L' plane at $T>T_{CDW}$, and (ii) anomalies in the electronic dispersion reflecting a sizable impact of phonons on it. A diffuse scattering precursor, characteristic of soft phonons, is observed at room temperature (RT) and leads to the full collapse of the low-energy phonon $(ω_1)$ with propagation vector (0.25 0 −0.3) r.l.u. We show that the frequency and linewidth of this mode are anisotropic in momentum space, reflecting the momentum dependence of the electron-phonon interaction (EPI), hence demonstrating that the origin of the CDW is, to a much larger extent, due to the momentum dependent EPI with a small contribution from nesting. The pressure dependence of the $ω_1$ soft mode remains nearly constant up to 13 GPa at RT, with only a modest softening before the transition to the high-pressure monoclinic C2/m phase. The wide set of experimental data is well captured by our state-of-the art first-principles anharmonic calculations with the inclusion of van der Waals corrections in the exchange-correlation functional. The comprehensive description of the electronic and dynamical properties of VSe$_2$ reported here adds important pieces of information to the understanding of the electronic modulations in the family of transition-metal dichalcogenides.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. PETRA-S (FS-PETRA-S)
3. FS-SXQM (FS-SXQM)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. FS-Proposal: I-20220825 EC (I-20220825-EC) (I-20220825-EC)

Experiment(s):

1. PETRA Beamline P09 (PETRA III)

Appears in the scientific report 2024

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Electronics and Telecommunications Collection ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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