| Project/Area Number |
63540243
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Teikyo University of Technology |
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Principal Investigator |
SUEZAWA Yoshitaka Teikyo University of Technology, Informatics, Associate Professor, 情報学部, 助教授 (30143738)
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| Co-Investigator(Kenkyū-buntansha) |
GONDO Yasuo Yokohama National University, Engineering, Professor, 工学部, 教授 (50017852)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Tunneling effect / Spin-dependent tunneling spectroscopy / Multilayered film / Ferromagnetic film / Electronic state / Magnetic valve effect / Tunneling junction / Ferromagnetic tunneling junction |
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| Research Abstract |
The purpose of this research is to acquire a basic understanding about the electronic state and magnetism of multilayered films, by means of spin-dependent tunneling. The results are as follows.
[1] Improvement of experimental system Tunneling characteristics of junctions can be obtained at temperatures between 3 and 300K, and in magnetic field up to 15 kOe. A cryogenic thermometer/controller (Palm Beach Cryophsics; Model 4075) has been introduced into the system owing to the present grant.
[2] Preparation of junctions and spin-dependent tunneling spectroscopy Those following types of junctions were examined. (1) AI(or FM)/Al_2O_3/FM junctions (FM: Ni or Co) (2) AI(or FM)/Al_2O_3/Al/FM junctions (3) FM/NiO/Ni junctions In preparing junctions of (i) and (2), a FM electrode was first deposited onto a glass substrate. A very thin Al film was then deposited over the first electrode. Its surface was oxidized to form a tunneling barrier of Al_2O_3. Finally, a counter electrode was evaporated across them. This method had been invented by us, and has advantages of flexibility in choosing the kind of the first electrode, and of the stability of Al_2O_3 barrier. Although the above mentioned final goal has not been reached yet, magnetic measurements such as magnetization curve and FMR were performed as well as tunneling experiments. The obtained results assure the future developments towards the goal.
[3] The observation of magnetic valve effect at room temperature In examining junctions of type(3), it was found that their tunneling conductance depends on the relative angle between the magnetizations of the FM and the first Ni electrode (magnetic valve effect), even at room temperature. This effect has been expected theoretically, however, only a few experimental results have been reported at low temperature.
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