Density-fluctuation spectra of dilute mixtures of /sup 3/He in superfluid /sup 4/He

Journal Article · Sun Aug 01 04:00:00 EDT 1982 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.26.1374· OSTI ID:7062317

Luecke, M; Szprynger, A

The density-fluctuation spectra S/sub i/j(k,..omega..) (i,j = 3,4) are evaluated with a matrix dispersion-relation representation in terms of characteristic frequencies and complex self-energies by the incorporation of damping via decay into /sup 3/He quasiparticle-quasihole excitations and by the use of renormalized fluctuation frequencies. The hybridization of /sup 4/He rotons with /sup 3/He quasiparticle excitations is too small to induce a peak splitting in S/sub 44/(k,..omega..) at the level crossing while the effective phonon-roton exchange potential between /sup 3/He quasiparticles splits the spectrum S/sub 33/(k,..omega..) into two peaks. The energy shift of the main neutron scattering intensity with respect to pure /sup 4/He agrees semiquantitatively with experiments. It is caused by partly competing effects listed in the order of their importance: frequency changes induced by the altered structure of /sup 4/He in the mixture, coupling between /sup 4/He and /sup 3/He restoring forces, hybridization with /sup 3/He quasiparticle-quasihole excitations, and the contribution of S/sub 34/(k,..omega..). Decay into two-mode density excitations is investigated within a mode-coupling approximation.

• Research Organization: Institut fuer Festkoerperforschung der Kernforschungsanlage Juelich, Postfach 1913, D-5170 Juelich, West Germany
• OSTI ID: 7062317
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 26:3; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DENSITY
DISPERSION RELATIONS
DISPERSIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXCHANGE INTERACTIONS
FLUCTUATIONS
FLUIDS
HELIUM 3
HELIUM 4
HELIUM II
HELIUM ISOTOPES
INTERACTIONS
ISOTOPES
LIGHT NUCLEI
MATRICES
MIXTURES
NUCLEI
PHONONS
PHYSICAL PROPERTIES
QUANTUM FLUIDS
QUASI PARTICLES
RENORMALIZATION
ROTONS
SPECTRA
STABLE ISOTOPES
VARIATIONS