2001 Fiscal Year Final Research Report Summary
Theoretical Study on Superconductor - Magnet Multilayers
| Project/Area Number |
11640352
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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 | Kobe University |
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Principal Investigator |
KUBOKI Kazuhiro Kobe University, Faculty of Science, Associate Professor, 理学部, 助教授 (50231296)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Unconventional superconductivity / magnetism / proximity effect / multilayer / high-Tc super conductivity / p-wave superconductivity |
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| Research Abstract |
Theoretical study has been carried out on the electronic properties of multilayers composed of unconventional superconductors and itinerant ferro/antiferromagnets. We treat a tight binding model on a square lattice with attractive (repulsive) interactions between nearest-neighbor sites (on-site) to describe the superconductivity (magnetism). Then we derive the Bogoliubov de Gennes (BdG) equations which describe the spatial variations of superconducting order parameters (SCOP) and magnetization using mean-field approximation. These BdG equations are solved numerically in a fully self-consistent way. We found the following :
(1) Near the interface between the superconductor and the (anti)ferromagnet, surface state where SCOP and magnetization coexist appears due to the I proximity effect.
(2) Near the interface the SCOP's with different symmetries from that of the bulk are induced. In particular, even if the SCOP has a spin-singlet symmetry in the bulk, spin-triplet SCOP can occur.
We have also examined the effect of impurities, since they always exist in real systems, and so it is necessary to examine the effect on the superconducting state in order to compare the theoretical results with experiments.
(3) It turns out the SCOP s with different symmetries from that of the bulk is induces around the impurity. Also spontaneous spin currents can appear near a magnetic impurity with spin-orbit interactions.
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