2003 Fiscal Year Final Research Report Summary
Photo-enhanced magnetization in semiconductors thin films incorporating magnetic dots
| Project/Area Number |
12450007
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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 |
Applied materials science/Crystal engineering
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
MUNEKATA Hiroo Tokyo Institute of Technology School of Science and Technology, Imaging Science and Engineering Laboratory, Professor, 大学院・理工学研究科, 教授 (60270922)
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| Project Period (FY) |
2000 – 2003
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| Keywords | Spintronics / Magnetic-Semiconductor Hybrid Structures / Photo-magnetization / Metamagnet / Cooperative Phenomenon / Nano-technology |
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| Research Abstract |
Enhancement of magnetization by the light illumination at room temperature (RT) has been reported in the year 2000 for semiconductor-magnetic composite films prepared by the alternative deposition of Fe and GaAs on GaAs(001) substrates at high substrate temperature of 580 "C. While this was a very encouraging achievement for the future applications such as the wireless micro-electronic mechanical system, the origin of the photo-enhanced magnetization (PEM) has remained unclear. It was partly because of the fact that those samples consisted of polycrystalline, granular structures whose constituent ingredients were not well engineered nor controlled. This research was initiated with the aim to identify the key materials and elucidate the mechanism of PEM.
Systematic studies of samples prepared by the alternative deposition of Fe_3Ga_<2-x>As_x and GaAs were carried out with various deposition sequences and different substrate temperatures T_<s-> GaN-based composite structures were also inv
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estigated. It was found that the samples prepared by molecular beam deposition with the stacking the unit of [100-nm GaAs/50-nm Fe_3Ga_<2-x>As_x/100-nm GaAs] at T_s = 600℃ exhibit significant PEM effect. Metallurgical evaluation by nano-electron probe analysis has revealed that metamagnetic metal Fe_3Ga_4 is responsible for the observed PEM. It was discussed that this compound was formed as a consequence of the interlayer diffusion process between GaAs and Fe_3Ga_<2-x>As. The hypothesis of the inter-particle interaction model, which was introduced at the initial stage of the study in 2000. was found not to be the principle mechanism for the observed PEM effect.
Systematic studies on power dependence of PEM suggest that the increase of magnetization is primarily dominated by the light-induced heating, whereas pure photonic excitation may also contribute the PEM, as manifested itself by the fact that the magnitude of PEM exceeds beyond the maximum value that can be expected from simple heating. This novel effect should be pursued in the future work. Less
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