| Project/Area Number |
02452035
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
固体物性
|
|---|
| Research Institution | University of Tokyo |
|---|
Principal Investigator |
KAGOSHIMA Seiichi University of Tokyo, Department of Pure and Applied Sciences, Professor, 教養学部, 教授 (30114432)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Hayao Toho University, Department of Chemistry, Professor, 理学部, 教授 (60057635)
OSADA Toshihito University of Tokyo, Research Center for Advanced Science and Technology, Lectur, 先端科学技術研究センター, 講師 (00192526)
|
|---|
| Project Period (FY) |
1990 – 1992
|
| Keywords | Organic Conductor / Low Dimensional Conductor / Transition Metal Elements / Metal-Insulator Transition / Reentrance / Magnetoresistance |
|---|
| Research Abstract |
The purpose of the present study is to clarify roles of transition metal delectrons in electronic properties of organic low-dimensional conductors having transition metal ions. The experimental research was focused to investigation of properties of conduction electrons predominantly in DCNQI-Cu salts. In dmit salts characterization of electronic properties was made. Special effort was made in studying electronic properties near the reentrance transition of (DMeDCNQI)_2Cu.
The followings are important results obtained in the present work: (1) The average valence of the copper ion in DCNQI-Cu slats was verified experimentally to be +4/3. (3) The magnetic structure of the anti-ferromagnetic state below about 8 K was made clear in the insulating state of DCNQI-Cu salts having the three-fold structure along the c-axis. (4) The reentrance transition in DMeDCNQI-Cu salt is accompanied with anomalies in the magnetic susceptibility, the three-fold structure, and the distortion around the copper ion. (5) Near the reentrance transition of DCNQI-Cu salts properties characteristic of the insulating state are present already in the metallic state. Furthermore magnetic fields as low as 10 T stabilize the insulating state. (6) In dmit salts both electron- and hole-like superconductivities were found. In addition both one- and two-dimensional properties were found depending on species of the metal ion.
We clarified that the electronic state of DCNQI-Cu salts is described in terms of the Peierls instability in the one-dimensional band formed by pi electrons of DCNQI, the Mott transition of the band formed predominantly by the d-electrons of copper ions, the Jahn-Teller effect of copper ions, and electronphonon interactions in the "soft" lattice. It is remained unsolved to reveal microscopic mechanisms of the reentrance transition.
|
