2003 Fiscal Year Final Research Report Summary
^<13>C-NMR Study of the Organic Superconductor near the Superconductor-Insulator Phase Boundary
| Project/Area Number |
14540316
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅱ(磁性・金属・低温)
|
|---|
| Research Institution | Hokkaido University |
|---|
Principal Investigator |
KAWAMOTO Atsushi Hokkaido University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (60251691)
|
|---|
| Project Period (FY) |
2002 – 2003
|
| Keywords | ^<13>C-NMR / κ-(BEDT-TTF)_2Cu[N(CN)_2]Br / strong correlated etectorn system / field-induced metal-insulator transition / Knight-shift / the spin-lattice relaxation rate / phase separation / partially deuteraion |
|---|
| Research Abstract |
^<13>C-NMR study on non-deulerated and partially deuterated κ-(BEDT-TTF)_2Cu[N(CN)_2]Br is reported, where BEDT-TTF is bis(ethylenedithio)tetra-thiafulvalene. By using the BEDT-TTF molecule having ^<13>C-enriched on only one side of the central carbon sites, we could estimate the density of states from the Knight-shift and the spin-lattice relaxation rate. Although the reduced mass effect predicted from the specific heat measurement was not observed in the ^<13>C-NMR, the melal-to-anliferromagnetic phase transition was observed with the phase separation around 18K on the half-deuterated κ-(BEDT-TTF)_2Cu[N(CN)_2]Br under a high magnetic field. Such a transition does not occur under a zero or low field on the **lf-deuterated sal. These results suggest a first order field-induced metal-insulator transition. These findings can explain the complex phenomena near the phase boundary under a high magnetic field. We also found that the phase separation is observed at around T^* with the applied field parallel to the conducting layer, unlike partially deuterated κ-(BEDT-TTF-d[n,n])_2Cu[N(CN)_2]Br. The former result suggests the field induces AF transition. the latter result suggests there is the field direction dependence of the M-1 phase separation behavior in κ-(BEDT-TTF-d[4,4])_2Cu[N(CN)_2]Br.
|
