2013 Fiscal Year Final Research Report
Low-temperature magnetization dymanics of TM-Al-O (TM=Fe and Co) granular magnetic films
Project/Area Number |
23560027
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Research Field |
Thin film/Surface and interfacial physical properties
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Research Institution | Ishinomaki Senshu University |
Principal Investigator |
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Project Period (FY) |
2011 – 2013
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Keywords | 磁性薄膜材料 / レーザー分光学 / ブリルアン散乱 / 磁化動力学 / 低温 |
Research Abstract |
We prepared a closed-cycle refrigerator for low-temperature Brillouin light scattering (BLS) study under external magnetic fields. We also improved the performances of our BLS apparutus for long spectrum-accumulation. With these apparutus we successfully observed scattering from super-paramagnetic (SPM) excitations for Co-Al-O films in a temparture range of between 300K and 15K under magetic fields of between 2.0kOe and 4.5 kOe. We developed a theoretical model for SPM BLS spectrum. We could analyze the observed spectra with the theoretical model. We found an anomalous temperature behavior of the peak frequency and width at around 150 K. This anomalous behavior can be attributed to a dispersion effect due to a coupling between precession of particle magnetization and relaxation with a low activation energy and a fast relaxation time of an order of 10 ps. We are planning extensive BLS studies of spin waves from ferromagentic thin films at low temperatures under magnetic fields.
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