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Neutron scattering study of the excitation spectrum of solid helium at ultra-low temperatures

Blackburn, Elizabeth LU ; Goodkind, J. M. ; Sinha, S. K. ; Broholm, C. ; Copley, John and Erwin, Ross (2008) In Pramana - Journal of Physics 71(4). p.673-678
Abstract
There has been a resurgence of interest in the properties of solid helium due to the recent discovery of non-classical rotational inertia (NCRI) in solid 4He by Chan and coworkers below 200 mK which they have interpreted as a transition to a ‘supersolid’ phase. We have carried out a series of elastic and inelastic neutron scattering measurements on single crystals of hcp 4He at temperatures down to 60 mK. While we have found no direct evidence of any change in the excitation spectrum at low temperatures, we have found that the excitation spectrum of solid 4He shows several interesting features, including extra branches in addition to the phonon branches. We interpret these extra branches as single particle excitations due to propagating... (More)
There has been a resurgence of interest in the properties of solid helium due to the recent discovery of non-classical rotational inertia (NCRI) in solid 4He by Chan and coworkers below 200 mK which they have interpreted as a transition to a ‘supersolid’ phase. We have carried out a series of elastic and inelastic neutron scattering measurements on single crystals of hcp 4He at temperatures down to 60 mK. While we have found no direct evidence of any change in the excitation spectrum at low temperatures, we have found that the excitation spectrum of solid 4He shows several interesting features, including extra branches in addition to the phonon branches. We interpret these extra branches as single particle excitations due to propagating vacancy waves, which map on to the famous ‘roton minimum’ long known in the excitation spectrum of superfluid liquid 4He. The results show that in fact solid 4He shares several features in common with the superfluid. (Less)
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author
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publishing date
type
Contribution to journal
publication status
published
subject
in
Pramana - Journal of Physics
volume
71
issue
4
pages
673 - 678
publisher
Springer
external identifiers
  • scopus:54249169656
ISSN
0973-7111
DOI
10.1007/s12043-008-0255-1
language
English
LU publication?
no
id
3e1a7c4f-0624-4968-890f-0498f96f3cfc
alternative location
https://link.springer.com/article/10.1007/s12043-008-0255-1
date added to LUP
2019-01-17 11:10:19
date last changed
2022-04-10 05:19:36
@article{3e1a7c4f-0624-4968-890f-0498f96f3cfc,
  abstract     = {{There has been a resurgence of interest in the properties of solid helium due to the recent discovery of non-classical rotational inertia (NCRI) in solid 4He by Chan and coworkers below 200 mK which they have interpreted as a transition to a ‘supersolid’ phase. We have carried out a series of elastic and inelastic neutron scattering measurements on single crystals of hcp 4He at temperatures down to 60 mK. While we have found no direct evidence of any change in the excitation spectrum at low temperatures, we have found that the excitation spectrum of solid 4He shows several interesting features, including extra branches in addition to the phonon branches. We interpret these extra branches as single particle excitations due to propagating vacancy waves, which map on to the famous ‘roton minimum’ long known in the excitation spectrum of superfluid liquid 4He. The results show that in fact solid 4He shares several features in common with the superfluid.}},
  author       = {{Blackburn, Elizabeth and Goodkind, J. M. and Sinha, S. K. and Broholm, C. and Copley, John and Erwin, Ross}},
  issn         = {{0973-7111}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{4}},
  pages        = {{673--678}},
  publisher    = {{Springer}},
  series       = {{Pramana - Journal of Physics}},
  title        = {{Neutron scattering study of the excitation spectrum of solid helium at ultra-low temperatures}},
  url          = {{http://dx.doi.org/10.1007/s12043-008-0255-1}},
  doi          = {{10.1007/s12043-008-0255-1}},
  volume       = {{71}},
  year         = {{2008}},
}