nano-scale real-space observation of surface two-dimensional electron system under ultra-low temperature and magnetic field
| Project/Area Number |
12450020
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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 |
表面界面物性
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HASEGAWA Yukio Institute for Solid State Physics, The University of Tokyo, Associate Professor, 物性研究所, 助教授 (80252493)
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| Co-Investigator(Kenkyū-buntansha) |
EGUCHI Toyoaki Institute for Solid State Physics, The University of Tokyo, Research Associate, 物性研究所, 助手 (70308196)
SAKAI Akira Faculty of Engineering, Kyoto Univ., Professor, 工学研究科, 教授 (80143543)
KOMORI Fumio Institute for Solid State Physics, The University of Tokyo, Associate Professor, 物性研究所, 助教授 (60170388)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥14,300,000 (Direct Cost: ¥14,300,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2000: ¥12,100,000 (Direct Cost: ¥12,100,000)
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| Keywords | scanning tunneling microscopy / electron standing waves / surface states / two-dimensional electronic states / 表面電子状態 / 2次元電子系 |
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| Research Abstract |
We set up ultrahigh vacuum scanning tunneling microscope (UHV-STM) which can be operated under ultra-low temperature and high magnetic field, and confirmed that it works at 4K under a magnetic field of 11T. Using the instrument, we were successfully able to take images of standing wave pattern spreading in several hundred angstrom on Au(111) and Cu(111) surfaces.
We observed standing wave images on Pd/Au(111) and Pd/Cu(111) surfaces, trying to find a method to control and reduce electron density occupied in the surface electronic states, and found that a period of electron standing waves observed on monolayer-high Pd thin film is longer than those observed on Au(111) or Cu(111) substrate. The longer period on Pd layers indicates higher energy level of the surface states on the Pd layer, and thus lower electron density in the states than the substrates. The modification of the surface states is explained by considering a formation mechanism of the surface states, and is attributed to the fact that an energy level of the surface states is located just below the lower edge of the L gap of Pd electronic states. For the final goal of our project: characterization of surface two-dimensional electron system with STM in high spatial resolution, the above result is a first step since electron density in the surface states has to be reduced in order to observe effects of magnetic field to the 2D electron system.
We also observed some adsorbates on the Au(111) surface which show contrast variation in STM with a amount of magnetic field. They appear as a bright spot under no magnetic field, but at high magnetic field (6T) they show a donut-like contrast with a same period of oscillation with the standing waves. We are now trying to elucidate a mechanism of the contrast variation through more controlled experiments and a collaboration with a theoretical group.
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Report
(3 results)
Research Products
(9 results)
