Studies on Quantum Fluid Dynamics of Rotating Superfluid Helium-3

利用中国科学院固体物理研究所研制的超低温旋转恒温器，以世界上最高的1转/秒的转速，将^3He样品冷却到低于mK的温度，我们研究了：1）超流A相在直径为0.1 mm和0.2 mm的两种圆柱形样品池中的流体动力学。对于直径为0.1mm的样品池，我们成功地控制了旋转，冷却条件和磁场的3种织构。这些织构之一被发现是Mermin-Ho织构（M-H）。我们通过核磁共振观察到自旋波信号定位在M-H的软核处，并从自旋波频率的旋转依赖性，我们得出结论，宏观角动量附着在软核上。宏观角动量可能来源于A相中库珀对的内禀角动量。对于直径为0.2的样品，我们观察到两种织构（可能是M-H织构和反旋织构）。增加额 ...更多信息 在M-H中的旋转速度，M-H首先通过在圆筒中引入n=2的涡流而从n=-1翻转到n=+1。当进一步增加转速时，n=2的涡流被引入到n=+1的M-H。我们讨论了量子化涡旋的成核和湮灭。当样品冷却到超流转变温度T_c以上时，通过旋转和磁场的相对取向，可以控制样品的M-H和反旋两种织构。这是一种爱因斯坦-巴内特效应，目前还没有任何解释。2)旋转气凝胶多孔材料中超流^3He中的量子化涡旋。在A相中，顶点的结构可以是奇异的，其核心尺寸为相干长度为100_0。在B相中，我们观察到量子涡旋被引入到气凝胶中，但是涡旋被气凝胶强烈地钉扎。即使在旋转停止后，钉扎也能维持很长时间的超电流。这种行为类似于非常硬的II型超导体中量子通量的蠕变现象。我们研究了气凝胶中的钉扎和涡旋的产生。3)在间距小于10 μm偶极相干长度的窄平行板中寻找超流a相中的新涡旋。在这个样本单元中，序参数的l-向量和d-向量彼此垂直。这种结构不同于体超流体。当转速增加时，发生Freedericksz转变。进一步增加旋转，然后涡旋开始进入样品。从涡旋的临界成核速度值较大，我们推测该涡旋应该是核尺寸为φ_0的相涡旋。少

By using a rotating ultra-low temperature cryostat constructed at Institute for Solid State Physics, which rotates at the word-highest rotation speed of 1 rotation/sec and cools the ^3He sample down to sub mK temperatures, we studied 1)fluid dynamics of superfluid-A phase in two kinds of cylindrical sample cells with 0.1 mm and 0.2 mm diameters. For the case of 0.1 mm diameter sample cell, we succeeded to control 3 kinds of textures by rotation, cooling conditions, and magnetic fields. One of these textures was found to be the Mermin-Ho textures(M-H). We observed a spin wave signal localized at the soft core of the M-H by NMR and from rotation dependence of the spin wave frequency, we concluded that a macroscopic angular momentum attached to the soft core,. The macroscopic angular momentum may come from the intrinsic angular momentum of Cooper pair in A-phase. For the case of 0.2 diameter sample, we observed two kinds of textures (probably the M-H and Disgyration textures). As increasi … More ng a rotation speed in the M-H, the M-H first flips from n=-1 to n=+1 by introduction of a vortex with n=2 in the cylinder. As further increasing the rotation speed, a vortex with n=2 is introduced to the M-H with n=+1. We discussed the nucleation and annihilation of quantized vortices. We could control the two textures of the M-H and the Disgyration by relative orientation between the rotation and magnetic field when we cooled the sample through the superfluid transition temperature T_c. This is a kind of Einstein-Barnett effectand there is not yet any explanation. 2)quantized vortex in superfluid ^3He in aerogel porous material under rotation. In A-phase, the structure of the vertex can be a singular one with a core size of the coherence length of ξ_0. In B-phase, we observed the quantum vortex introduced to the aerogel but the vortices were strongly pinned by aerogel. The pinning maintained super-current for a long time even after the rotation was stopped. This behavior is resembled to the creep phenomena of quantized flux in very hard type II superconductors. We studied pinning and creation of vortices in aerogel. 3)search for a new vortex in superfluid a-phase in a narrow parallel plate with a spacing smaller than the dipole coherence length of 10 μm. In this sample cell, the l-and d-vector of the order-parameter are perpendicular with each other. This configuration is different from a bulk superfluid. When the rotation speed increased, Freedericksz transition occurred. Further increasing the rotation, then vortex started to go into the sample. From the large value of the critical velocity of nucleation of the vortex, we speculated that the vortex should be the phase vortex with the core size of ξ_0. Less