| Project/Area Number |
62460019
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 | Hokkaido University |
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Principal Investigator |
NOMURA Kazushige Faculty of Science, Hokkaido University, 理学部, 助教授 (80128579)
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| Co-Investigator(Kenkyū-buntansha) |
SAMBONGI Takashi Faculty of Science, Hokkaido University, 理学部, 教授 (60000791)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥7,100,000 (Direct Cost: ¥7,100,000)
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| Keywords | Carge Density Wave / Sliding / Pinning / Narrow Band Noise / Hydrostatic Pressure / 相関距離 / しきい電場 / トンネル顕微鏡静水圧 / 擬一次元導体 |
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| Research Abstract |
We have done the electric measurement and the STM (Scanning Tunneling Microscope) observation to investigate the sliding of CDW (Charge Density Wave).
In the electric measurement, we measured the electric conductivity, the threshold field for sliding, the narrow band noise and the transient voltage oscillation in K@>D20.3@>D2MoO_3 with varying the temperature and the applied hydrostatic pressure systematically. The behavior of threshold field was explained with the variation of phase correlation length of CDW and these results confirmed the weak pinning mechanism. The results of the narrow band noise and the transient voltage oscillation indicated that the CDW begins to slide with the long correlation length of phase of velocity modulation and changes to the stationary sliding state with decreasing the velocity correlation. Then, the CDW behaves as a rigid body at the beginning of sliding and as a more deformable one at the stationary sliding state.
In the STM measurement, at first we constructed the STM apparatus operating in the low temperature region. Using this apparatus, we tried to observe the image of super-lattice-structure due to the CDW in K_<0.3>MoO_3, but didn't succeed to obtain the atomic image nor the super-structure clearly. The reason is mainly attributed to the contamination of sample surface and the control of the gas absorption is the future problem. While, we observed a sharp peak in the spectra of tunneling current under a bias current. This peak was considered to be generated by the periodic modulation of the distance between the tunneling tip and the surface atom of sample with the sliding motion of CDW. This is the first direct observation of sliding CDW at the sample surface. It was confirmed that the CDW is sliding faster at the surface than the inside of sample.
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