Origin of Superconductivity and Latent Charge Density Wave in NbS2

Heil, Christoph;Poncé, Samuel;Lambert, Henry;Schlipf, Martin;Giustino, Feliciano;et.al.
(2017) Physical Review Letters — Vol. 119, n° 8, p. 87003 (2017)

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Authors
  • Heil, ChristophDepartment of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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  • Lambert, HenryDepartment of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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  • Schlipf, MartinDepartment of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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  • Giustino, FelicianoDepartment of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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Abstract
We elucidate the origin of the phonon-mediated superconductivity in 2H-NbS2 using the ab initio anisotropic Migdal-Eliashberg theory including Coulomb interactions. We demonstrate that superconductivity is associated with Fermi surface hot spots exhibiting an unusually strong electron-phonon interaction. The electron-lattice coupling is dominated by low-energy anharmonic phonons, which place the system on the verge of a charge density wave instability. We also provide definitive evidence for twogap superconductivity in 2H-NbS2, and show that the low- and high-energy peaks observed in tunneling spectra correspond to the Γ- and K-centered Fermi surface pockets, respectively. The present findings call for further efforts to determine whether our proposed mechanism underpins superconductivity in the whole family of metallic transition metal dichalcogenides.
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Citations

Heil, C., Poncé, S., Lambert, H., Schlipf, M., Margine, E. R., & Giustino, F. (2017). Origin of Superconductivity and Latent Charge Density Wave in NbS2. Physical Review Letters, 119(8), 87003. https://doi.org/10.1103/physrevlett.119.087003 (Original work published 2017)