title: Observation of a superfluid component within solid helium.
abstract: We demonstrate by neutron scattering that a localized superfluid component exists at high pressures within solid helium in aerogel. Its existence is deduced from the observation of two sharp phonon-roton spectra which are clearly distinguishable from modes in bulk superfluid helium. These roton excitations exhibit different roton gap parameters than the roton observed in the bulk fluid at freezing pressure. One of the roton modes disappears after annealing the samples. Comparison with theoretical calculations suggests that the model that reproduces the observed data best is that of superfluid double layers within the solid and at the helium-substrate interface.
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: H
authors.initials: H
authors.lastname: Lauter
authors.forename: V
authors.initials: V
authors.lastname: Apaja
authors.forename: I
authors.initials: I
authors.lastname: Kalinin
authors.forename: E
authors.initials: E
authors.lastname: Kats
authors.forename: M
authors.initials: M
authors.lastname: Koza
authors.forename: E
authors.initials: E
authors.lastname: Krotscheck
authors.forename: V V
authors.initials: VV
authors.lastname: Lauter
authors.forename: A V
authors.initials: AV
authors.lastname: Puchkov