2022 Fiscal Year Annual Research Report
| Project/Area Number |
22J14746
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| Allocation Type | Single-year Grants |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
WANG TIANCHUN 東京大学, 工学系研究科, 特別研究員(DC2)
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| Project Period (FY) |
2022-04-22 – 2024-03-31
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| Keywords | superconductivity / ab initio calculation / hydride superconductor / electron-phonon coupling |
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| Outline of Annual Research Achievements |
We have established an efficient method based on the Migdal-Eliashberg formalism combined with auxiliary intermediate representation basis functions.
Using this formalism, we applied it on C-S-H systems as well as doped LaH10 system, which is a high-Tc hydride superconductor. Combining structure prediction algorithm and ab initio Tc method, we performed a thorough study in C-S-H convex hull, and found that theoretical predicted Tc of C-doped H3S has a large deviation compared to the experimental value.
For LaH10, we have constructed a systematical screening process to search for optimal doping elements to increase Tc, and we successfully found that Ca is a promising candidate to increase Tc for about 15 %.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
From our research proposal, we were aiming to establish and develop an ab initio scheme for phonon-mediated superconductors, and generalized our method to unconventional method. So far, we have had a thorough study on electron-phonon interaction and the screened Coulomb interaction. These two factors have been taken into the current version of our method. In addition, the anharmonicity effect of phonon has also been added, which is very important at hydrogen rich compounds. Based on this, studies on unconventional studies can be performed. By comparing the theoretical predicted values and experimental values, we can figure out which part of the interaction plays a dominant rule in unconventional superconducting systems.
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| Strategy for Future Research Activity |
We are planning to continue to develop our ab initio superconductivity method and apply it to other superconductors. The development of the method will includes the consideration of plasmon effect and anharmonicity effect of phonon. The bubble term correction to phonon self-energy will also be included.
Furthermore, the mechanism and microscopic explanation of the high-Tc in hydride superconductors will also be one of our research topics. Based on the efficient scheme we have established, we are looking for a universal explanation to probe into high-Tc superconductors at high pressure.
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