Observation of a massive phason in a charge-density-wave insulator.

Autor: Kim S; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Lv Y; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Sun XQ; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Zhao C; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Science and Engineering Department, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Bielinski N; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Murzabekova A; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Qu K; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Duncan RA; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA., Nguyen QLD; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA., Trigo M; Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA., Shoemaker DP; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Materials Science and Engineering Department, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Bradlyn B; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA., Mahmood F; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA. fahad@illinois.edu.; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA. fahad@illinois.edu.
Jazyk: angličtina
Zdroj: Nature materials [Nat Mater] 2023 Apr; Vol. 22 (4), pp. 429-433. Date of Electronic Publication: 2023 Mar 09.
DOI: 10.1038/s41563-023-01504-5
Abstrakt: The lowest-lying fundamental excitation of an incommensurate charge-density-wave material is believed to be a massless phason-a collective modulation of the phase of the charge-density-wave order parameter. However, long-range Coulomb interactions should push the phason energy up to the plasma energy of the charge-density-wave condensate, resulting in a massive phason and fully gapped spectrum 1 . Using time-domain terahertz emission spectroscopy, we investigate this issue in (TaSe 4 ) 2 I, a quasi-one-dimensional charge-density-wave insulator. On transient photoexcitation at low temperatures, we find the material strikingly emits coherent, narrowband terahertz radiation. The frequency, polarization and temperature dependences of the emitted radiation imply the existence of a phason that acquires mass by coupling to long-range Coulomb interactions. Our observations underscore the role of long-range interactions in determining the nature of collective excitations in materials with modulated charge or spin order.
(© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)
Databáze: MEDLINE
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