Elementary excitations in superfluid sup 3 He- sup 4 He mixtures: Pressure and temperature dependence

Journal Article · Tue May 01 04:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.8732· OSTI ID:6807120

Fak, B ^[1]; Guckelsberger, K; Koerfer, M; Scherm, R ^[2]; Dianoux, A J ^[3]

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1. Department of Neutron Research, Uppsala University, 611 82 Nykoeping, (Sweden)
2. Physikalisch-Technische Bundesanstalt, 3300 Braunschweig, (Federal Republic of Germany)
3. Institut Laue-Langevin, 38042 Grenoble (France)

The neutron-scattering function for dilute mixtures of {sup 3}He (1% and 5%) in superfluid {sup 4}He at pressures of 0, 10, and 18 bars and temperatures in the range from 0.07 to 1.5 K has been determined for wave vectors between 0.4 and 2.2 A{sup {minus}1}. This is the first such measurement for {sup 3}He-{sup 4}He mixtures at temperatures below the Fermi temperature. The line shape of the {sup 3}He particle-hole excitation is well described by a nearly-free-Fermi-gas model at all temperatures. The {sup 3}He quasiparticle spectrum is derived for wave vectors in the range 0.9{lt}{ital Q}{lt}1.7 A{sup {minus}1}. The results deviate from the quadratic Landau-Pomeranchuk spectrum and are in good agreement with thermodynamical measurements. No rotonlike minimum is observed. We find strong indications of a crossover between the {sup 3}He particle-hole band and the {sup 4}He roton excitation. The pressure and temperature dependence of the shift and broadening of the {sup 4}He phonon-roton peak is derived. The main features are reproduced in a simple model for Landau damping.

• OSTI ID: 6807120
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:13; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DISPERSION RELATIONS
DISPERSIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FLUIDS
HELIUM 3
HELIUM 4
HELIUM II
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MEDIUM PRESSURE
MIXTURES
NUCLEI
PHONONS
PRESSURE DEPENDENCE
QUANTUM FLUIDS
QUASI PARTICLES
ROTONS
STABLE ISOTOPES
SUPERFLUIDITY
TEMPERATURE DEPENDENCE
ULTRALOW TEMPERATURE