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Title: Softening of a flat phonon mode in the kagome ScV6Sn6

Journal Article · · Nature Communications
ORCiD logo [1];  [2];  [2];  [3]; ORCiD logo [4];  [5];  [6];  [7]; ORCiD logo [7];  [5]; ORCiD logo [8]; ORCiD logo [7];  [6]; ORCiD logo [1];  [8];  [1]; ORCiD logo [7]; ORCiD logo [9]; ORCiD logo [10]
  1. European Synchrotron Radiation Facility (ESRF), Grenoble (France)
  2. Donostia International Physics Center (DIPC), San Sebastian (Spain)
  3. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics; University of Chinese Academy of Sciences, Beijing (China)
  4. Princeton Univ., NJ (United States)
  5. Donostia International Physics Center (DIPC), San Sebastian (Spain); Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)
  6. Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
  7. Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)
  8. Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  9. Donostia International Physics Center (DIPC), San Sebastian (Spain); Princeton Univ., NJ (United States); Basque Foundation for Science, Bilbao (Spain). IKERBASQUE
  10. Donostia International Physics Center (DIPC), San Sebastian (Spain); Basque Foundation for Science, Bilbao (Spain). IKERBASQUE

Geometrically frustrated kagome lattices are raising as novel platforms to engineer correlated topological electron flat bands that are prominent to electronic instabilities. Here, we demonstrate a phonon softening at the kz = π plane in ScV6Sn6. The low energy longitudinal phonon collapses at ~98 K and q = $$\tfrac{1}{3}$$ $$\tfrac{1}{3}$$ $$\tfrac{1}{2}$$ due to the electron-phonon interaction, without the emergence of long-range charge order which sets in at a different propagation vector qCDW = $$\tfrac{1}{3}$$ $$\tfrac{1}{3}$$ $$\tfrac{1}{3}$$. Theoretical calculations corroborate the experimental finding to indicate that the leading instability is located at $$\tfrac{1}{3}$$ $$\tfrac{1}{3}$$ $$\tfrac{1}{2}$$ of a rather flat mode. We relate the phonon renormalization to the orbital-resolved susceptibility of the trigonal Sn atoms and explain the approximately flat phonon dispersion. Our data report the first example of the collapse of a kagome bosonic mode and promote the 166 compounds of kagomes as primary candidates to explore correlated flat phonon-topological flat electron physics.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
AC02-06CH11357; SC0012704
OSTI ID:
2204335
Journal Information:
Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 14; ISSN 2041-1723
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English

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