2000 Fiscal Year Final Research Report Summary
Theoretical studies for the intrinsic Josephson effect and the collective excitations in high-Tc superconductors
| Project/Area Number |
11640332
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Tohoku University |
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Principal Investigator |
KOYAMA Tomio Tohoku Univ., IMR, Research Associate, 金属材料研究所, 助手 (30153696)
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| Project Period (FY) |
1999 – 2000
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| Keywords | high-Tc superconductors / intrinsic Josephson effect / Josephson plasma / Coulomb blockade |
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| Research Abstract |
The CuO2 layers in high-Tc cuprates are responsible for the high-temperature superconductivity in these systems. The coupling between Cu02 layers in high-Tc superconductors is very weak. As a result, the Josephson effect appears in the c-axis transport phenomena even in single crystals of these superconductors, which is called the intrinsic Josephson effect. In this research project I have investigated theoretically the c-axis transport properties related to the intrinsic Josephson effects in high-Tc superconductors. I have constructed a complete quantum theory for the Josephson plasma oscillations observed in these superconductors. The effects of the quasi-particles on the plasma excitations were clarified in this theory. The c-axis charge dynamics in an array of the intrinsic Josephson junctions reveals the size dependence when the in-plane (ab-plane) area is decreased. This phenomena is caused by the Coulomb blockade effect. The plasma oscillations in this system become unstable when the in-plane area decreases below some critical value, Wc. The c-axis charge dynamics in the system with an in-plane area less than Wc is dominated by the single Cooper-pair tunneling. I have developed a renormalization group theory for the Coulomb blockade effect in an array of the intrinsic Josephson junctions. The explicit expression for Wc was derived.
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