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Title: Temperature-tunable Fano resonance induced by strong coupling between Weyl fermions and phonons in TaAs

Strong coupling between discrete phonon and continuous electron–hole pair excitations can induce a pronounced asymmetry in the phonon line shape, known as the Fano resonance. This effect has been observed in various systems. We reveal explicit evidence for strong coupling between an infrared-active phonon and electronic transitions near the Weyl points through the observation of a Fano resonance in the Weyl semimetal TaAs. The resulting asymmetry in the phonon line shape, conspicuous at low temperatures, diminishes continuously with increasing temperature. Furthermore, this behaviour originates from the suppression of electronic transitions near the Weyl points due to the decreasing occupation of electronic states below the Fermi level (EF) with increasing temperature, as well as Pauli blocking caused by thermally excited electrons above EF. These findings not only elucidate the mechanism governing the tunable Fano resonance but also open a route for exploring exotic physical phenomena through phonon properties in Weyl semimetals.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7] ;  [2] ;  [2] ;  [5]
  1. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics; Center for High Pressure Science and Technology Advanced Research, Beijing (China)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center for Integrated Nanotechnologies
  3. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics
  4. Center for High Pressure Science and Technology Advanced Research, Beijing (China)
  5. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics; Collaborative Innovation Center of Quantum Matter, Beijing (China)
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Center for Integrated Nanotechnologies and Theoretical Division
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Associate Directorate for Chemistry, Life, and Earth Sciences
Publication Date:
Report Number(s):
LA-UR-16-26540
Journal ID: ISSN 2041-1723
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Material Science; Fano resonance, Weyl semimetals
OSTI Identifier:
1357119