| Project/Area Number |
08454098
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Okayama University |
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Principal Investigator |
YAMAZAKI Hitoshi Okayama University, Faculty of Science Professor, 理学部, 教授 (40013495)
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| Co-Investigator(Kenkyū-buntansha) |
MINO Michinobu Okayama University, Faculty of Science, Research Associate, 理学部, 助手 (30222326)
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| Project Period (FY) |
1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1996: ¥6,900,000 (Direct Cost: ¥6,900,000)
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| Keywords | Spin-waves / Magnon / Bose Condensation / Parametric Excitation / YIG / Microwave Rediation / パラメトリック |
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| Research Abstract |
Nonequilibrium states of magnon having the specific wave vector can be excited by parametric exciation, which is achieved by applying intense microwave magnetic field parallel to the magnetic moments in a ferromagnet. These magnons loose energy by magnon-magnon scattering processes, resulting to condensed states at the bottom of the magnon band. The purpose of this research is to clarify the condensed states by detecting microwave emission from the condensed magnon. The nonlinear excitation experiments were performed by applying magnetic field parallel to the easy magnetization axis [111] of a sphere of Yttrium-Iron-Garnet (YIG) single crystal in diameter of 1 mm. Microwave of 9.6 GHz from a synthesizer was amplified to the maximum 16 W by a Traveling Wave Tube Amplifier (TWTA). Microwave signal was detected by a small pick-up coil wounded around the sample. The microwave signal was observed by a microwave spectrum analyzer with using low-pass filter and low-noise amplifier. Frequency of the detected microwave was different from that of exciation microwave. The detected emission has a frequency of lower than the bottom of the spin-wave band. The second and third higher harmonics are also observed. Line shapes and frequency shift of the emission depend on temperature. Nonlinear interaction between photons in a microwave cavity and monequilibrium magnon pairs becomes important and this coupled system is under investigation by both experimentally and theoretically.
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