Observation of a new superfluid phase for 3He embedded in nematically ordered aerogel
Observation of a new superfluid phase for 3He embedded in nematically ordered aerogel
复制标题
观察嵌入向列有序气凝胶中的 3He 的新超流相
作者：
N. Zhelev;M. Reichl;T. S. Abhilash;E. Smith;K. Nguyen;E. Mueller;J. Parpia
在零磁场下的体超流体3He中，除了在高压和高温下有利于a相出现外，b相在任何地方都稳定存在。纳米结构小于超流体相干长度的气凝胶是将无序引入超流体的唯一手段。在这里，我们使用一个扭摆来研究3He，它被限制在一个极各向异性、向列有序的气凝胶中，气凝胶由~ 10纳米厚的氧化铝链组成，间隔为~ 100纳米，平行于摆轴排列。随着温度的变化（在不同压力下），超流体部分的发展中的扭结对应于相变。在超流体状态中可以看到两个这样的转变，我们将低压下最接近Tc的超流体相确定为极性态，这是在大块3He中看不到的相。预测各向异性无序会改变3he中超流体状态的稳定性并导致新相的产生。在这里，Zhelev等人报道了3He在极各向异性有序气凝胶中的相变特征，包括一个新的极性相。
In bulk superfluid 3He at zero magnetic field, two phases emerge with the B-phase stable everywhere except at high pressures and temperatures, where the A-phase is favoured. Aerogels with nanostructure smaller than the superfluid coherence length are the only means to introduce disorder into the superfluid. Here we use a torsion pendulum to study 3He confined in an extremely anisotropic, nematically ordered aerogel consisting of ∼10 nm-thick alumina strands, spaced by ∼100 nm, and aligned parallel to the pendulum axis. Kinks in the development of the superfluid fraction (at various pressures) as the temperature is varied correspond to phase transitions. Two such transitions are seen in the superfluid state, and we identify the superfluid phase closest to Tc at low pressure as the polar state, a phase that is not seen in bulk 3He. Anisotropic disorder is predicted to change the stability of the superfluid state in3He and leads to new phases. Here, Zhelev et al. report signatures of the phase transitions in 3He confined in an extremely anisotropic ordered aerogel including a new polar phase.