Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2011 Dec 23;107(26):265301. doi: 10.1103/PhysRevLett.107.265301. Epub 2011 Dec 22.
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.
我们通过中子散射证明，在气凝胶中的固体氦中存在局部超流成分。其存在是通过观察两个明显区别于体超流氦模式的尖锐声子-回旋子光谱推断出来的。这些回旋激发具有与在冻结压力下体流体中观察到的回旋不同的回旋间隙参数。其中一个回旋模式在退火后消失。与理论计算的比较表明，最好地再现了观测数据的模型是固体中以及氦-基底界面处的超流双层模型。
