| Project/Area Number |
17560586
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Ishinomaki Senshu University |
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Principal Investigator |
YOSHIHARA Akira Ishinomaki Senshu University, Faculty of Science and Engineering, Professor, 理工学部, 教授 (40166989)
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| Co-Investigator(Kenkyū-buntansha) |
OHNUMA Shigehiro Research Institute for Electric and Magnetic Materials, Senior Researcher, 主任研究員 (50142633)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Brillouin scattering / Granular magnetic films / Spin wave / Inter-granule exchange coupling / Magnetic constant / Resistivity / 磁気励起 / 交換相互作用 |
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| Research Abstract |
2005 :
1. We have examined superparamagnetic (SPM) excitations in a sputtered Co_<51>Al_<18>O_<31> film by Brillouin light scattering (BLS) at room temperature in magnetic fields of up to 6 kOe. We could observe transient behaviors from heavily damped spectra in disorder state below 0.5 kOe to the magnetostatic spin-wave (SW) spectra in the field-induced ferromagnetic state above 4.5 kOe. This is the very first BLS observation of the SPM excitations. We also confirmed that dipole coupling dominates the excitation frequencies. We have a plan to investigate the SPM excitations al low temperatures.
2. We examined BLS from SWs in ferromagnetic Co_<78>Al_<18>O_<18>, Co_<66>Al_<11>O_<23> and Co_<63>Al_<13>O_<24> films in magnetic fields of up to 4.0 kOe at room temperature, and determined the magnetic constants including the exchange field H_<ex> for each film. Combining the exchange fields and the specific resistivities, we found an inverse-square law between the reisitivity ρ and the exchang
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e field H_<ex> : ρ_<Co>=22.1x H_<ex>^<-2> (μΩ.cm). Here, H_<ex> is in kOe unit.
2006 :
We consider that the inverse-square law is a characteristic magneto-electric property of the metal-nonmetal soft magnetic granular films. We selected Fe-Al-0 films as another model material, and measured BLS from the SWs at room temperature. We prepared Fe_<83>Al_<19>O_8, Fe_<76>Al_<12>O_<12>, Fe_<64>Al_<10>O_<17> and Fe_<62>Al_<19>O_<19> films in this study. Again, we obtained BLS spectra from SWs and determined their frequencies as a function of the magnetic field. We determined the exchange fields, and confirmed the inverse-square law given by ρ_<Fe>=30.3 x H_<ex>^<-2> (μΩ.cm) for the Fe-Al-O films.
In this two years project we have obtained two important and quite new results. (1) We have clearly shown that inter-granule exchange coupling really exists in soft ferromagnetic nano-granular films. (2) Now it is possible to determine the exchange field constant of the TM-Al-0 (TM=Fe, Co) granular films through resistivity measurement. Less
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