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Electronic structure and lattice dynamics of 1T-VSe2 : Origin of the three-dimensional charge density wave
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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19
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Physical Review B, Volume 109, issue 3, pp. 1-19
Abstract
To characterize in detail the charge density wave (CDW) transition of 1T-VSe2, 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>TCDW, which leads to a depletion of the density of states in the ML-M'L' plane at T<TCDW, 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 (ω1) 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 ω1 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 VSe2 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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Funding Information: We thank V. Strocov for fruitful discussions. J.D. thanks the Department of Education of the Basque Government for a predoctoral fellowship (Grant No. PRE-2020-1-0220). V.P., D.S., and S.B-C. acknowledge financial support from the MINECO of Spain through Grants No. PID2021-122609NB-C22 and No. PID2021-122609NB-C21, respectively. S.B.-C. is also supported by MCIN and the European Union Next Generation No. EU/PRTR-C17.I1, as well as by IKUR Strategy under the collaboration agreement between Ikerbasque Foundation and DIPC on behalf of the Department of Education of the Basque Government. I.E. acknowledges funding from the Department of Education, Universities and Research of the Eusko Jaurlaritza, and the University of the Basque Country UPV/EHU (Grant No. IT1527-22) and the Spanish Ministerio de Ciencia e Innovación (Grant PID2022-142861NA-100). C.P. acknowledges financial support from MINECO Project No. PID2021-125927NB-C21. A.O.F. thanks the Academy of Finland Project No. 349696. M.C. is cofunded by the European Research Council (ERC, DELIGHT, No. 101052708). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. We thank the ESRF for provision of synchrotron radiation facilities under Proposals No. HC-4941, No. HC-4513, and No. HC-4873. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at beamline P09 at PETRA III at DESY. Beamtime was allocated for Proposal No. 20220825 EC. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science user facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. LOREA beamline at ALBA Synchrotron Light Source was cofunded by the European Regional Development Fund (ERDF) within the Framework of the Smart Growth Operative Programme. We also thank J. Prat for the invaluable technical support during ARPES experiments at LOREA. Experiments at the ISIS Neutron and Muon Source were supported by a beamtime allocation No. RB2220362 from the Science and Technology Facilities Council. The data is available at Ref. . We thank CESGA (Centro de Supercomputacion de Galicia) for the computing facilities. Publisher Copyright: © 2024 American Physical Society.
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Diego, J, Subires, D, Said, A H, Chaney, D A, Korshunov, A, Garbarino, G, Diekmann, F, Mahatha, S K, Pardo, V, Wilkinson, J M, Lord, J S, Strempfer, J, Perez, P J B, Francoual, S, Popescu, C, Tallarida, M, Dai, J, Bianco, R, Monacelli, L, Calandra, M, Bosak, A, Mauri, F, Rossnagel, K, Fumega, A O, Errea, I & Blanco-Canosa, S 2024, 'Electronic structure and lattice dynamics of 1T-VSe2 : Origin of the three-dimensional charge density wave', Physical Review B, vol. 109, no. 3, 035133, pp. 1-19. https://doi.org/10.1103/PhysRevB.109.035133