1989 Fiscal Year Final Research Report Summary
Spin Dynamics of uudd Phase of Helium-3.
| Project/Area Number |
62460035
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | Kyoto University |
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Principal Investigator |
HIRAI Akira Kyoto Univ. Phys. Dept. Assoc. Prof., 理学部, 助教授 (70025287)
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| Co-Investigator(Kenkyū-buntansha) |
TSUBOTA Makoto Tohoku Univ. Inst. Fluid Assoc. Prof., 流体科学研究所, 助教授 (10197759)
OHMI Tetsuo Kyoto Univ. Phys. Dept. Assoc. Prof., 理学部, 助教授 (70025435)
TSUNETO Toshihiko Kyoto Univ. Phys. Dept. Prof., 理学部, 教授 (30025275)
MIZUSAKI Takao Kyoto Univ. Phys. Dept. Lecturer, 理学部, 講師 (20025448)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Solid Helium-3 / Ultralow Temperatures / ^3He NMR / Nuclear Spin Ordering / Antiferromagnetic Relaxation / Multi-magnon Processes / Superconducting Magnet / 超伝導マグネット |
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| Research Abstract |
We have studied spin dynamics in uudd phase of solid ^3He. This nuclear spin ordered phase appears at ultralow temperatures (below 1 mK.) under melting pressure (about 3.4 MPa.) and under low external magnetic field (below 0.42 T). The purpose of this study is to study experimentally and theoretically spin relaxation mechanism. non-linear spin dynamics, and chaotic spin notions, predicted on this peculiar spin system.
1. It was rather easy to grow a single crystal of solid ^3He. Then, we tried to grow a sample of single magnetic domain of uudd phase (by applying electric or magnetic field gradient or by epitaxial growth on MgO surface), but so far in vain.
2. We made a small superconducting magnet with current shim coils and a superconducting tube to shield the ambient magnetic field, to produce a homogeneous magnetic field and controlled magnetic field gradient at the simple position.
3. We studied the domain structure of the sample by using an "NMR imaging" technique with the above-mentioned magnet. We found that the sizes of the domain are rather large and a single crystal of the order of several mm^3 is divided into only a few domains.
4. We found the evidence that a single crystal of bcc solid ^3He distorts axially and shows a twin structure, when the magnetic phase transition to the ordered phase occurs.
5. By using a cw-NMR method, we measured the external magnetic field and the temperature dependences of the NMR line width. to study the relaxation processes. We have also studied theoretically the line width due to the "multi-magnon processes". The calculated results account for the observed experimental data satisfactorily.
Thus, the microscopic mechanism of the antiferromagnetic relaxation in a uudd phase is now clearly understood.
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