ePubs
The open archive for STFC research publications
Home
About ePubs
Content Policies
News
Help
Privacy/Cookies
Suggest an Enhancement
Contact ePubs
Full Record Details
Persistent URL
http://purl.org/net/epubs/work/66060
Record Status
Checked
Record Id
66060
Title
Phonon-roton modes of liquid ^4He beyond the roton in the porous medium MCM-41
Contributors
RT Azuah (NIST Center for Neutron Research)
,
SO Diallo (Delaware U.)
,
MA Adams (STFC Rutherford Appleton Lab.)
,
O Kirichek (STFC Rutherford Appleton Lab.)
,
HR Glyde (Delaware U.)
Abstract
We present neutron scattering measurements of the phonon-roton (P-R) mode of superfluid 4He confined in 47 Å MCM-41 at T=0.5 K at wave vectors, Q, beyond the roton wave vector (QR=1.92 Å−1). Measurements beyond the roton require access to high wave vectors (up to Q=4 Å−1) with excellent energy resolution and high statistical precision. Only one previous measurement in porous media (in aerogel) with low statistical precision has been reported. At T=0.5 K, we find that the P-R mode in MCM-41 extends out to wave vector Q≃3.6 Å−1, with the same energy and zero width (within precision) as observed in bulk superfluid 4He. Layer modes in the roton region are also observed. Specifically, the P-R mode energy, ωQ, increases with Q for Q>QR and reaches a plateau at a maximum energy ωQ=2Δ where Δ is the roton energy, Δ=0.74 ± 0.01 meV in MCM-41. This upper limit means the P-R mode decays to two rotons if its energy exceeds 2Δ. It also means that the P-R mode does not decay to two-layers modes. If the P-R could decay to two-layer modes, ωQ would plateau at a lower energy, ωQ=2ΔL, where ΔL=0.60 meV is the energy of the roton-like minimum of the layer mode. Rather the P-R mode and the layer modes observed in porous media appear to be quite different modes with little interaction between them.
Organisation
ISIS
,
ISIS-OSIRIS
,
STFC
Keywords
ISIS 2013
Funding Information
Related Research Object(s):
Licence Information:
Language
English (EN)
Type
Details
URI(s)
Local file(s)
Year
Journal Article
Phys Rev B
88, no. 2 (2013): 024510.
doi:10.1103/PhysRevB.88.024510
2013
Showing record 1 of 1
Recent Additions
Browse Organisations
Browse Journals/Series
Login to add & manage publications and access information for OA publishing
Username:
Password:
Useful Links
Chadwick & RAL Libraries
SHERPA FACT
SHERPA RoMEO
SHERPA JULIET
Journal Checker Tool
Google Scholar