2007 Fiscal Year Final Research Report Summary
Science of Nano-Wire Metal Complexes with Strong Electron-Correlation
| Project/Area Number |
15GS0216
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| Research Category |
Grant-in-Aid for Creative Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Institution | Tohoku University (2004-2007)
Tokyo Metropolitan University (2003) |
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Principal Investigator |
YAMASHITA Masahiro Tohoku University, Graduate School of Science, Professor (60167707)
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| Co-Investigator(Kenkyū-buntansha) |
YONEMITSU Kenji National Institutes of Natural Science, Institute for Molecular Science, Associate Professor (60270823)
OKAMOTO Hiroshi The University of Tokyo, Graduate School of Frontier Science, Professor (40201991)
KATO Masako Hokkaido University, Graduate School of Science, Professor (80214401)
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| Project Period (FY) |
2003 – 2007
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| Keywords | Third-Order Optical Nonlinearity / Strong Electron Correlation / Electron-Phonon Interaction / Peierls Transition / Nano-Wire / Mott-Insulator / Fastener Effect / Ultra-Fast Optical Communication |
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| Research Abstract |
Quasi-one-dimensional halogen-bridged Pd compounds take a Pd(II)-Pd(IV) mixed-valence state or charge-density-wave state or Peierls Insulator due to the electron-phonon interaction. In order to realize a Pd(III) Mott-Insulator we used the sulphonic acid counter anions with long alkyl chains. In the raw of the five alkyl chain, the Pd compound shows the phase transition from the Pd(II)-Pd(IV) Peierls Insulator into the Pd(III) Mott-Insulator about 200K with hysteresis, which is the inverse Peierls transition. This phenomena were evidenced by ESR, X-ray single-crystal analyses, single-crystal reflection spectra, electrical conductivities, etc. In the case of the ten and twelve alkyl chains, the Pd(III) Mott-insulators are the ground state even in mom temperature, which is the first example. These interesting phenomena are well explained by the fastener effect or chemical pressure of the long alkyl chains. In the Pd(III) Mott-Insulator at 15 K the photo-irradiation with the energy of the charge transfer band (0.5eV) produced the Pd(II)-Pd(IV) Peierls Insulator state, while the photo-irradiation with L5 eV produced the metallic state. Such photo-induced phase transitions occurred in femto-seconds, which are available for the ultra-fast optical communication.
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