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中原子的大零点运动导致原子之间的直接交换相互作用，这就是核磁性的原因。我们研究了固体^3He在低压相的高压样品以及固体^3He的高压相。这项研究对于揭示固体^3He在低压和高压阶段的核磁性的整个分布非常重要。我们测量了尼尔温度从49到355muK的样品的磁化率作为温度和频率的函数。我们发现核有序温度范围内存在异常敏感性。我们还观察到，从磁化率推导出来的能流弛豫时间在整个转变过程中急剧减少了两个数量级。这一事实可以通过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34muK的测量表明它具有铁磁倾向，并预测其有序温度为12muK，这个温度很难达到。我们采用了对固体^3He中的核子自旋进行消磁的方法，利用卡皮查热阻带来的长弛豫时间来达到如此低的温度。固体^3He退磁过程中及退磁后，固体^3He压强从2T下降到0.01T，降低了60 Pa。退磁后磁化率降低了200 pH。然而，我们没有观察到排序转换的显着特征。观察排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49μK，高压相的测量最低温度为34μK，是固体^3He的最低温度记录。