Studies on Quantum Fluid Dynamics of Rotating Superfluid Helium-3

利用固体物理研究所建造的旋转超低温恒温器，以世界上最高的转速1转/秒旋转，将~3He样品冷却到亚MK温度，研究了1)超流体-A相在两种直径分别为0.1 mm和0.2 mm的圆柱形样品池中的流体动力学。对于直径为0.1 mm的样品池，我们成功地通过旋转、冷却条件和磁场控制了3种织构。其中一种纹理被发现是Mermin-Ho纹理(M-H)。我们用核磁共振观察到一个定域在M-H软核上的自旋波信号，并从自旋波频率随旋转的变化得出结论：软核上附着着一个宏观角动量。宏观角动量可能来自于A相中库珀对的本征角动量。对于直径为0.2的样品，我们观察到了两种织构(可能是M-H织构和偏转织构)。随着…的增加在M-H中，当旋转速度增加时，M-H首先通过在圆柱体中引入n=2的旋涡，从n=-1反转到n=+1。随着旋转速度的进一步提高，在n=+1的M-H中引入了一个n=2的涡旋。我们讨论了量子化涡旋的成核和湮灭。当我们通过超流转变温度T_c冷却样品时，我们可以通过旋转和磁场之间的相对取向来控制M-H和偏转两种织构，这是一种爱因斯坦-巴尼特效应，目前还没有任何解释。2)气凝胶多孔材料中超流态的量子化涡旋。在A阶段，顶点的结构可以是核心尺寸为ξ_0相干长度的奇异结构。在B相，我们观察到量子涡旋被引入到气凝胶中，但涡旋被气凝胶强烈钉扎。即使在停止旋转后，钉扎仍保持较长时间的过电流。这一行为类似于超硬II型超导体中量子化磁通的蠕变现象。我们研究了气凝胶中的钉扎和涡旋的产生。3)在间距小于10μm偶极子相干长度的平行窄平板中寻找超流α相中的新涡旋。在该样品池中，序参数的L矢量和d矢量相互垂直。这种构型不同于块状超流体。随着转速的增加，发生了弗里德里克兹相变。进一步增加旋转，然后漩涡开始进入样本。根据涡核形成的临界速度较大，推测该涡核尺寸为ξ_0的相位涡。较少

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