2004 Fiscal Year Final Research Report Summary
Synthesis and phase control of fullerene based superstructured materials
| Project/Area Number |
15340106
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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 |
Condensed matter physics II
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| Research Institution | Tohoku University |
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Principal Investigator |
TAGUCHI Yasujiro Tohoku University, Institute for Materials Research, associate professor, 金属材料研究所, 助教授 (70301132)
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| Co-Investigator(Kenkyū-buntansha) |
IWASA Yoshihiro Tohoku University, Institute for Materials Research, professor, 金属材料研究所, 教授 (20184864)
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| Project Period (FY) |
2003 – 2004
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| Keywords | fullerene / alkali metal intercalation / insulator-superconductor transition / solid solution / electronic specific heat / density of states / Jahn-Teller interaction / orbital degeneracy |
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| Research Abstract |
In this fiscal year, we have tried to reveal universality and unique points in fullerene based compounds, dealing with layered nitride superconductors that also exhibit band insulator to superconductor transition similarly to the case of alkali metal intercalated fullerides. We have succeeded in preparing a series of samples with continuously changed Li-content (x<0.12), and have confirmed that these are of single phase by using synchrotron X-ray diffraction technique at BL2B-02, SPring 8. This fact makes striking contrast with the case of fullerides where only line phases exist and the intermediate phases can not be obtained, clearly indicating the anomalous solid state chemistry of fullerene compounds. Also, we have performed the specific heat measurements of layered nitride superconductors in magnetic fields, and have found that the normal-state Sommerfeld constant γ is very small (=1.0 mJ/mol K^2). We can obtain very small electron-phonon coupling constant λ(=0.22) by using this value and the density of states at the Fermi level predicted by several band calculations. This fact is in accord with the relatively narrow phonon lines observed in Raman scattering spectra. This fact also makes striking contrast with the fullerides where superconductivity is mediated by high frequency phonon with intermediate electron-phonon coupling strength, indicating the importance of Jahn-Teller interaction where the fullerene molecules show deformation. It is theoretically pointed out that Jahn-Teller interaction that couples with the degenerate LUMO orbitals is important in fullerides, and our result is consistent with this.
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Research Products
(21 results)
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[Journal Article] Determination of the orbital moment and crystal-field splitting in LaTiO32005
Author(s)
H.W.Haverkort, Z.Hu, A.Tanaka, G.Ghiringhelli, M.Cwik, T.Lorenz, C.Schussler-Langeheine, S.V.Streltsov, A.S.Mylnikova, V.I.Anisimov, C.de Nadai, N.B.Brookes, H.H.Hsieh, H.J.Lin, C.T.Chen, T.Mizokawa, Y.Taguchi, Y.Tokura, D.I.Khomskii, L.H.Tjeng
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Journal Title
Physical Review Letters Vol.94
Pages: 056401-1-056401-4
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Fully gapped single-particle excitations in lightly doped cuprates2004
Author(s)
K.M.Shen, T.Yoshida, D H.Lu, F.Ronning, N.P.Armitage, W.S.Lee, X.J.Zhou, A.Damascelli, D.L.Feng, N.J.C.Ingle, H.Eisaki, Y.Kohsaka, H.Takagi, T.Kakeshita, S.Uchida, P.K.Mang, M.Greven, Y.Onose, Y.Taguchi, Y.Tokura, S.Komiya, Y.Ando, M.Azuma, M.Takano, A.Fujimori, Z.-X.Shen
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Journal Title
Physcal Review B Vol.69
Pages: 054503-1-054503-5
Description
「研究成果報告書概要(欧文)」より
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