2015 Fiscal Year Research-status Report
界面拡散層の抑制により大きな磁気誘電および磁気光学効果を有するナノ複相薄膜の創製
| Project/Area Number |
15K18231
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| Research Institution | Tohoku University |
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Principal Investigator |
張 亦文 東北大学, 学際科学フロンティア研究所, 助教 (30579959)
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| Project Period (FY) |
2015-04-01 – 2017-03-31
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| Keywords | DPS / nanocomposite films / BTO-Co / C-Co / magnetic property / electrical property |
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| Outline of Annual Research Achievements |
As micro-electronic devices undergo the innovation, multifunctional materials are required. Recently, it is found that a kind of metal-insulator nanocomposite films exhibit giant magneto-dielectric responses or surface plasmon resonance enhanced magneto-optical effects. To obtain such properties, it is crucial to make abrupt hetero-interfaces in the nanocomposite films. However, it is usually difficult. Because conventional deposition systems keep the metal and the ceramic deposition in the same atmosphere, which easily induce the intermixing at interface. To overcome this problem, the newly Differential pressure sputtering (DPS) method, has been developed and used for controlling the interface of the nano-composite films in this research. In this year, first, I have designed and revised the separator for the two small chambers. Second, by this DPS method, I made the BTO-Co nanocomposite films with clear interface between Co particles and BTO ceramics phase, which show high resistivity, dielectric constant and good magnetic properties. Third, I also challenged the C-Co nano-composite films. From the morphology of TEM, the C-Co nano-composite films show typically nano-composite structure with clear interface between the amorphous C matrix and Co particles. As increasing the chamber pressure, the resistivity increases. These films show both high resistivity and superpara-magnetic properties, simultaneously.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
[1]I have designed and revised the separator for the two small chambers. In DPS method, the metal and the ceramic deposition have been separated in the two small chambers. By decreasing the clearance inside, I reduced the cross-contamination between metal and ceramics deposition obviously.
[2] By this DPS method, I made the BTO-Co nanocomposite films with clear interface between Co particles and BTO ceramics phase, which show high resistivity, dielectric constant and good magnetic properties. HRTEM observation shows that the size of metal Co particles have been controlled to be smaller than 2 nm, by changing Co layer thickness below 2.5 nm. The films show superparamagnetic properties. With lower Co layer thickness, the BTO-Co films exhibit high resistivity, and dielectric constant tested at 1 kHz of these BTO-Co films increases from about 10 to 40, by changing the Co layer thickness.
[3] The C-Co nano-composite films were deposited onto Si, Pt/Si and quartz substrates by hybrid CVD-sputtering method, which consists of plasma enhanced chemical vapor deposition and co-sputtering of a metal Co target. The C-Co nano-composite films have been produced successfully. By increasing the chamber pressure form 0.01 to 0.05 Torr, the resistivity increases obviously, which shows large change range. By observing morphology of the films from TEM, the C-Co nano-composite films with high pressure show clear interface between the amorphous C matrix and Co particles. Moreover, the films show good superpara-magnetic properties.
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| Strategy for Future Research Activity |
[1] In next year, I will keep trying other new nanocomposite films, such as ZnO-Co. For improving crystallinity of the films, the further development of DPS method will be considered and proceeded.
[2] On the base of research results in this year, the BTO-Co and C-Co nanocomposite films will be studied schematically to improve the electrical and magnetic properties. The relationship between structure and properties will be discussed in detail.
[3]Then, I will challenge to find the giant magneto-dielectric responses and surface plasmon resonance enhanced magneto-optical effects in the nanocomposite films discussed above. The magnesium of these new properties will be studied and discussed. The co-research and measurement will performed with our cooperator group in Denjiken in Sendai.
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| Causes of Carryover |
For the further experiment, new type sputtering targets is need. But the time is not enough to buy them in this year.
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| Expenditure Plan for Carryover Budget |
I will buy the new type sputtering targets by this amount in next fiscal year.
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