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Nuclear Spin Order of High-Pressure Phase Solid ^3He in the Temperature Range of muK

muK温度范围内高压相固体^3He的核自旋有序

基本信息

批准号：
05452054
负责人：
MAMIYA Takayoshi
金额：
$ 4.93万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05452054/
关键词：
Solid helium 3 Ultralow temperature Nuclear spin order Micro Kelvin Nuclear magnetism Nuclear demagnetization Zero point motion Direct exchange interaction 非金属セル

项目摘要

A large zero point motion of atoms in solid ^3He leads to the direct exchange interactions among atoms, which is responsible for nuclear magnetism. We studied the high-pressure samples of the solid ^3He in the low pressure phase as well as the high-pressure phase of solid ^3He. This study is very important for disclosing the entire profile of the nuclear magnetism in solid ^3He across the low-pressure and high-pressure phases.We measured the magnetic susceptibility of samples with Neel temperatures from 49 to 355muK as a function of temperature and frequency. We discoverd anomalous susceptibility across the nuclear ordering temperatures. We also observed that the relaxation time of the energy flow deduced from the susceptibility decreased drastically by two orders of magnitude across the transition. This fact was explained by the multi-magnon processes of the energy flow in the ordered state.For the high-pressure phase of solid ^3He, we showd by the measurements down to 34muK that it had a ferromagnetic tendency and predicted that its ordering temperature was 12muK,which temperature was formidable to reach. We adopted the mehtod of demagnenizing the nucler spins in solid ^3He to reach that low temperature by taking advantage of the long relaxation time due to the Kapitza thermal resistance. The pressure of solid ^3He decreased 60 Pa during and after demagnetization of solid ^3He from 2T down to 0.01T.The susceptiblity decreased 200 pH after demagnetization. Howeverwe observed no significant signature of the ordering transition. The further trials of observing the ordering transition is in progress. We note that the Neel temperature of 49muK in the low-pressure phase and the lowest temperature of the measurement for the high-pressure phase 34 muK are the record low temperatures for the solid ^3He.

固体^3He中原子的大的零点运动导致原子间的直接交换作用，这是产生核磁性的原因。我们研究了低压相和高压相的^3He固体的高压样品。我们测量了Neel温度为49 ~ 355 μ K的样品的磁化率随温度和频率的变化关系。我们研究了不同核有序温度下的反常磁化率。我们还观察到，从磁化率推导出的能量流的弛豫时间急剧减少了两个数量级的过渡。这一现象可以用有序态能量流的多磁振子过程来解释。对于固体^3He的高压相，我们通过低至34 μ K的测量表明，它具有铁磁倾向，并预测其有序温度为12 μ K，这是一个难以达到的温度。我们采用了使固体^3He中的核自旋去镁的方法，利用Kapitza热阻所导致的长弛豫时间来达到这个低温。在固体^3He从2 T到0.01T的退磁过程中和退磁后，固体^3He的压强下降了60 Pa，退磁后的磁化率下降了200 pH。然而，我们没有观察到显着的签名的有序过渡。观察有序转变的进一步试验正在进行中。我们注意到，低压相的尼尔温度为49 μ K，高压相的最低测量温度为34 μ K，这是固体^3He的最低温度记录。