Pines’ demon observed as a 3D acoustic plasmon in Sr₂RuO₄
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- Husain, Ali A.
- Department of Physics and Materials Research Laboratory, University of Illinois, Urbana
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- Huang, Edwin W.
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois, Urbana
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- Mitrano, Matteo
- Department of Physics, Harvard University
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- Rak, Melinda S.
- Department of Physics and Materials Research Laboratory, University of Illinois, Urbana
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- Rubeck, Samantha I.
- Department of Physics and Materials Research Laboratory, University of Illinois, Urbana
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- Guo, Xuefei
- Department of Physics and Materials Research Laboratory, University of Illinois, Urbana
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- Yang, Hongbin
- Department of Chemistry and Chemical Biology, Rutgers University
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- Sow, Chanchal
- Department of Physics, Kyoto University; Present address: Department of Physics, Indian Institute of Technology
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- Maeno, Yoshiteru
- Department of Physics, Kyoto University; Toyota Riken - Kyoto Univ. Research Center (TRiKUC), KUIAS, Kyoto University
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- Uchoa, Bruno
- Department of Physics and Astronomy, University of Oklahom
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- Chiang, Tai C.
- Department of Physics and Materials Research Laboratory, University of Illinois, Urbana
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- Batson, Philip E.
- Department of Physics, Rutgers University
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- Phillips, Philip W.
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois, Urbana
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- Abbamonte, Peter
- Department of Physics and Materials Research Laboratory, University of Illinois, Urbana
Abstract
The characteristic excitation of a metal is its plasmon, which is a quantized collective oscillation of its electron density. In 1956, David Pines predicted that a distinct type of plasmon, dubbed a ‘demon’, could exist in three-dimensional (3D) metals containing more than one species of charge carrier. Consisting of out-of-phase movement of electrons in different bands, demons are acoustic, electrically neutral and do not couple to light, so have never been detected in an equilibrium, 3D metal. Nevertheless, demons are believed to be critical for diverse phenomena including phase transitions in mixed-valence semimetals, optical properties of metal nanoparticles, soundarons in Weyl semimetals and high-temperature superconductivity in, for example, metal hydrides. Here, we present evidence for a demon in Sr₂RuO₄ from momentum-resolved electron energy-loss spectroscopy. Formed of electrons in the β and γ bands, the demon is gapless with critical momentum qc = 0.08 reciprocal lattice units and room-temperature velocity v = (1.065 ± 0.12) × 10⁵ m s⁻¹ that undergoes a 31% renormalization upon cooling to 30 K because of coupling to the particle–hole continuum. The momentum dependence of the intensity of the demon confirms its neutral character. Our study confirms a 67-year old prediction and indicates that demons may be a pervasive feature of multiband metals.
Speak of the Demon: Discovery of strange behavior of new plasmons predicted in the 50s. 京都大学プレスリリース. 2023-09-25.
Journal
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- Nature
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Nature 621 (7977), 66-70, 2023-09-07
Springer Nature
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Details 詳細情報について
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- CRID
- 1050860377191854976
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- ISSN
- 14764687
- 00280836
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- HANDLE
- 2433/284976
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- Text Lang
- en
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- Article Type
- journal article
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- Data Source
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- IRDB