Observation of Zero-Sound at Atomic Wave-Vectors in a Monolayer of Liquid 3He

  • H. Godfrin
  • M. Meschke
  • H.-J. Lauter
  • H. M. Böhm
  • E. Krotscheck
  • M. Panholzer
Article

Abstract

The elementary excitations of a strongly interacting two-dimensional Fermi liquid have been investigated by inelastic neutron scattering in an experimental model system: a monolayer of liquid 3He adsorbed on graphite preplated by a monolayer of solid 4He. We observed for the first time the particle-hole excitations characterizing the Fermi liquid state of two-dimensional liquid 3He, and we were also able to identify the highly interesting zero-sound collective mode above a particle-hole band. Contrarily to bulk 3He, at low wave-vectors this mode lies very close to the particle-hole band. At intermediate wave-vectors, the collective mode enters the particle-hole band, where it is strongly broadened by Landau damping. At high wave-vectors, where the Landau theory is not applicable, the zero-sound collective mode reappears beyond the particle-hole band as a well defined excitation, with a dispersion relation quite similar to that of superfluid 4He. This spectacular effect is observed for the first time in a Fermi liquid (including plasmon excitations in electronic systems).

Keywords

Quantum fluids 3He Fermi liquid Excitations Inelastic neutron scattering 

PACS

67.10.-j 67.30.E- 67.30.em 71.27.+a 

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • H. Godfrin
    • 1
  • M. Meschke
    • 1
  • H.-J. Lauter
    • 2
  • H. M. Böhm
    • 3
  • E. Krotscheck
    • 3
  • M. Panholzer
    • 3
  1. 1.Institut NéelCNRS et Université Joseph FourierGrenoble Cedex 9France
  2. 2.Institut Laue-LangevinGrenoble Cedex 9France
  3. 3.Institute for Theoretical PhysicsJohannes Kepler UniversityLinzAustria

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