2000 Fiscal Year Final Research Report Summary
Development of Urtla-High Vacuum, Low Temperature, High Magnetic Field Scanning Tunneling Microscope.
| Project/Area Number |
10354011
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
機能・物性・材料
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
ENOKI Toshiaki Tokyo Institute of Technology, Graduate school of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (10113424)
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| Co-Investigator(Kenkyū-buntansha) |
OZAWA Kenichi Tokyo Institute of Technology, Graduate school of Science and Engineering, Research Associate, 大学院・理工学研究科, 助手 (00282822)
SATO Hirohiko Tokyo Institute of Technology, Graduate school of Science and Engineering, Research Associate, 大学院・理工学研究科, 助手 (90262261)
EDAMOTO Kazuyuki Tokyo Institute of Technology, Graduate school of Science and Engineering, Assistant professor, 大学院・理工学研究科, 教授 (80185123)
NAGAMURA Toshihiko UNISOKU Co. Ltd., President, 開発研究所, 所長
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| Project Period (FY) |
1998 – 2000
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| Keywords | ultra-high vacuum / low temperature / high magnetic field / STM / tunneling spectroscopy / nano-graphite / fluorinated graphite / local density of states |
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| Research Abstract |
We constructed an ultra-high vacuum, low-temperature scanning tunneling microscope, which could be operated under high magnetic field up to 11T and illumination of light. The lattice images of HOPG were observed at helium temperature under the magnetic field up to 11T.The tunneling spectra showing a CDW gap were successfully obtained for 2H-NbSe_2. However, well reproducible tunneling spectra could not be obtained for graphite. This is considered to be caused by that the spectra depend seriously on the condition of STM tips, producing random fluctuation of tunneling current, which is larger than the current intrinsic to the energy dependence of the density of states. It is necessary to characterize the STM tip condition for obtaining an optimum measurement condition. The improvement of data analysis is also important for obtaining high quality data of tunneling current. The observations of the superconducting gap and vortices are now under way. We tried to observe lattice images of locally fluorinated surface of HOPG and nano-sized graphene sheet on an HOPG substrate. The lattice image of fluorinated HOPG surface consists of fluorinated sites generated by the formation of covalent sp^3-bondings between carbon atoms and introduced fluorine atoms, which are surrounded by the region having a √<3>×√<3> superlattice. The lattice image is compared with that theoretically predicted. Nano-graphene sheet is prepared on an HOPG substrate by a combination of electrophoretic technique and heat treatment using nano-sized diamond particles. STM observations suggest that the prepared nano-graphene have an in-plane size of ca. 10nm and an inter-layer distance of 0.36-0.37nm. The inter-layer distance larger than that of bulk graphite (0.335nm) evidences a considerable reduction of the inter-layer interaction.
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