1998 Fiscal Year Final Research Report Summary
Brillouin spectroscopy of spin waves in metallic ferromagnetic crystals
| Project/Area Number |
09440142
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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 | Ishinomaki Senshu University |
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Principal Investigator |
YOSHIHARA Akira Ishinomaki Senshu University, Department of Basic Sciences, Associate Professor, 理工学部, 助教授 (40166989)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Brillouin scattering / spin wave / EuS / phase transition / demagnetization / Fe / Au superlattice / exchange coupling / anisotropy |
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| Research Abstract |
In this research project we have investigated thermally excited spin waves in various metallic ferromagnetic crystals by means of Brillouin light scattering (BLS).
In the first year of our project we have examined spin waves of a typical ferromagnetic semiconductor EuS single crystal in a wide temperature range between 7.5 K and 300 K including the ferromagnetic transition temperature at 16.5 K.We could observe magnetic scattering even at room temperature which is far above the transition temperature. However we could observe neither softeing of the spin wave frequency nor broadening of peak width around the transition temperature. We found that the spin wave frequencies in the ferromagnetic phase are much lower than the values evaluated from the magnetization of EuS and the applied magnetic field. This observation strongly indicates that the demagnetization coefficient near the surface illuminated by laser beam is much less than the value of 4p which is expected for a thin film. In order to clarify the demagnetization coefficient effect, we are planning a new BLS study of sputtered EuO thin films which also undergo a very similar ferromagnetic phase transition.
In the second year we have mainly investigated the interlayer exchange coupling phenomena of MBE prepared fine-layered Fe (n ML)/Au (n ML) (n=1 to 5) superlattices which can be regarded as regularly ordered Fe-Au alloy single crystals with D_<4h> tetragonal sysmetry. We have studied spin waves for both of integer and non-integer atomic layer superlattices. We found that the interlayer exchange coupling between the Fe layers across the Au layers is always ferromagnetic for our superlattices and becomes very weak around at 3 ML and 5 ML.This is the first observation of such even-odd effect of the interlayer exchange coupling phenomena in superlattice structures.
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Research Products
(14 results)
