2004 Fiscal Year Final Research Report Summary
Metal -insulator -superconductor phase separation in the highly correlated organic conductors near the Mott transition.
| Project/Area Number |
15540329
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics II
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
SASAKI Takahiko Tohoku University, Institute for Materials Research, Associate Professor, 金属材料研究所, 助教授 (20241565)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YONEYAMA Naoki Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (80312643)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Keywords | organic conductor / Mott transition / phase separation / Infrared reflectance spectra |
|---|
| Research Abstract |
Systematic investigation of the electronic phase separation on macroscopic scale has been performed in the organic Mott system κ-(BEDT-TTF)_2[N(CN)_2]Br. Real space imaging of the phase separation is obtained by means of scanning micro-region infrared spectroscopy (SMIS) using the synchrotron radiation (SR). Experimental evidence of the electronic phase separation has been obtained on the single crystal surface of the organic Mott system κ-[(h-BEDT-TTF)_<1-x>(d-BEDT-TTF)_x]_2Cu[N(CN)_2]Br, of which band width is controlled by the substitution ratio x between the hydrogenated BEDT-TTF molecule (h-BEDT-TTF) and the deuterated one (d-BEDT-TTF). SMIS measurements using SR enable us to show the macroscopic size of the domain structure of the insulating and metallic regions. This finding does not exclude the possibility of the nano-scale inhomogeneity inside each domains or each scanning spot because the obtained spectrum may result in the average of nano-scale inhomogeneity in the measured spot. But close agreement between the previous results of NMR and magnetization and present results suggests that the phase separation occurs on macroscopic scale. The observation of the micro-meter scale phase separation is different from the recent findings of the nano-scale electronic inhomogeneity in the strongly correlated transition metal oxide system, which is a filling controlled Mott system. We therefore expect that the nano-scale intrinsic inhomogeneity appears in the filling controlled Mott system without thermodynamic phase transition, and the macroscopic inhomogeneity, if it comes, should accompany the critical phenomena like as the phase transition and non-equilibrium state in the band width controlled Mott system. The origin of the phase separation found in this study must be the bistability of the antiferromagnetic Mott insulator and superconducting phases just at the first order Mott transition.
|
