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

Godfrin, H.; Meschke, Matthias; Läuter, H.; Böhm, Helga M.; Krotscheck, E.; Panholzer, Martin

doi:10.1007/s10909-009-9952-5

Cited by 11 publications

(13 citation statements)

References 18 publications

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“…34 Our Landau parameters do yield excellent agreement with this zero sound measurement. For bulk 3 He there has been some work on the polarization dependence of transport coefficients.…”

Section: Discussionsupporting

confidence: 67%

Transport in thin polarized Fermi-liquid films

Anderson

Miller

2015

Phys. Rev. B

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We calculate expressions for the state-dependent quasiparticle lifetime, the thermal conductivity κ, the shear viscosity η, and discuss the spin diffusion coefficient D for Fermi-liquid films in two dimensions. The expressions are valid for low temperatures and arbitrary polarization. In two dimensions, as in three dimensions, the integrals over the transition rates factor into energy and angular parts. However, the angular integrations contain a weak divergence. This problem is addressed using the method of Miyake and Mullin. The low-temperature expressions for the transport coefficients are essentially exact. We find that κ −1 ∼ T ln T , and η −1 ∼ T 2 for arbitrary polarizations 0 ≤ P ≤ 1. These results are in agreement with earlier zero-polarization results of Fu and Ebner, but are in contrast with the discontinuous change in temperature dependence from T 2 ln T at P = 0 to T 2 at 0 < P < 1 that was found by Miyake and Mullin for D. We note that the shear viscosity requires a unique analysis. We utilize previously determined values for the density and polarization dependent Landau parameters to calculate the transition probabilities in the lowest order "ℓ = 0 approximation", and thus we obtain predictions for the density, temperature and polarization dependence of the thermal conductivity, shear viscosity, and spin diffusion coefficient for thin 3 He films. Results are shown for second layer 3 He films on graphite, and thin 3 He-4 He superfluid mixtures. The density dependence is discussed in detail. For κ and η we find roughly an order of magnitude increase in magnitude from zero to full polarization. For D a simialr large increase is predicted from zero polarization to the polarization where D is a maximum (∼ 0.74).We discuss the applicability of 3 He thin films to the question of the existence of a universal lower bound for the ratio of the shear viscosity to the entropy density.

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“…34 Our Landau parameters do yield excellent agreement with this zero sound measurement. For bulk 3 He there has been some work on the polarization dependence of transport coefficients.…”

Section: Discussionsupporting

confidence: 67%

Transport in thin polarized Fermi-liquid films

Anderson

Miller

2015

Phys. Rev. B

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“…10, we pointed out that there exists a single measurement of a zero-sound speed for a 3 He film at zero polarization by Godfrin, Meschke, Lauter, Böhm, Krotscheck, and Panholzer. 25 Their substrate was graphite, the 3 He areal density was n = 0.049Å −2 , the wave vector was q = 5.5 nm −1 , and the energy transfer was ω = 0.68 ± 0.05 meV. This yields a zero-sound speed of c 0 ≈ 190 ± 14 m/s.…”

Section: Discussionmentioning

confidence: 98%

“…Since common experimental temperatures 25 are on the order of β −1 ∼ 5-10 mK, it is clear that for this system, phonon absorption is also frozen out because of the mismatch between accessible Fermi velocities and the substrate speed of sound.…”

Section: B Quasiparticle-phonon Collisionsmentioning

confidence: 99%

Zero sound and first sound in thin arbitrarily polarized Fermi-liquid films

Anderson

Miller

2013

Phys. Rev. B

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We study the propagation and attenuation of zero sound and first sound in thin, arbitrarily polarized Fermi-liquid films. Following Khalatnikov and Abrikosov, we solve Landau's linearized kinetic equation in the relaxation-time approximation for a complex speed of sound. Analytic solutions are obtained in the hydrodynamic and ballistic limits for arbitrary polarization. By solving the collision integral in two dimensions, we find the well-known result that quasiparticle-quasiparticle collisions contribute to the collision frequencies 1/τ σ , with a low-temperature term proportional to T 2 ln (T F σ /T ), where σ = ↑, ↓ is the spin state. If the films are adsorbed to a dynamic substrate, we find additional possible contributions to the collision frequency that come from quasiparticle-phonon interactions. We show, however, that for 3 He thin films, the mismatch between possible maximum values of the Fermi velocity and the substrate speed of sound freezes this contribution out at usual experimental temperatures. Thus, we can conclude that zero sound propagates at absolute zero in this type of adsorbed Fermi-liquid film. By utilizing previous results for the Landau parameters of an arbitrarily polarized 3 He film, we compute numerical solutions for the sound speeds and attenuation in the hydrodynamic and ballistic regimes, thereby studying the transition from first sound to zero sound as a function of temperature.

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“…The concept of elementary excitations was introduced by Landau to describe the low temperature behavior of quantum fluids: bosonic liquid 4 He and fermionic liquid 3 He. His elegant theory turned out to be the seed of the theoretical framework used presently to describe not only quantum fluids, but more generally condensed matter, nuclear and particle physics: i.e., all systems where strongly correlated matter plays an essential role.…”

Section: Introductionmentioning

confidence: 99%

“…His elegant theory turned out to be the seed of the theoretical framework used presently to describe not only quantum fluids, but more generally condensed matter, nuclear and particle physics: i.e., all systems where strongly correlated matter plays an essential role. Quantum fluids 4 He and 3 He are still the unavoidable reference and benchmark: these simple monoatomic and isotropic systems display macroscopic quantum phenomena: Bose-Einstein condensation in liquid 4 He and a pure Fermi Liquid state with a spherical Fermi surface, Cooper pairing of fermions in liquid 3 He... Thanks to these extraordinary properties, theoretical predictions on topological excitations, particle physics and cosmologic effects can be tested in helium at very low temperatures, as we would do in a test tube!…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional Fermi liquids sustain surprising roton-like plasmons beyond the particle-hole band

Sultan

Godfrin

Meschke

et al. 2012

J. Phys.: Conf. Ser.

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Using inelastic neutron scattering, we have investigated the elementary excitations of an isotropic two-dimensional Fermi liquid, 3 He adsorbed on graphite. We provide in this article a detailed account of the principles and methods which allowed measuring for the first time inelastic spectra on a liquid monolayer of 3 He, a strong neutron absorber. We also summarise the results presented at this Conference, and review our recent experimental and theoretical work on this this interacting many-body system. At low wave-vectors, near the edge of the particle-hole band, a mode identified as the zero-sound excitation by comparison to our theoretical calculations, is found as predicted at energies much lower than in bulk 3 He. The mode enters the particle-hole band, where it undergoes Landau damping. Surprisingly, however, intensity is observed in the neutron spectra at wave-vectors larger than twice the Fermi wavevector. This new branch is interpreted as the high wave-vector continuation of the zero-sound mode, in agreement with the theory. The results open new perspectives in the understanding of the dynamics of correlated fermions.

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

Cited by 11 publications

References 18 publications

Transport in thin polarized Fermi-liquid films

Transport in thin polarized Fermi-liquid films

Zero sound and first sound in thin arbitrarily polarized Fermi-liquid films

Two-dimensional Fermi liquids sustain surprising roton-like plasmons beyond the particle-hole band

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