Abstract
The local electronic state at every crystallographically independent molecular site was separately investigated in the organic superconductor using site-selective -NMR spectroscopy. The density of states (DOS) at three molecular sites shows independent temperature variation, which is caused by the long-range Coulomb interaction. Comparing the present results with those for a nonsuperconducting counterpart , we found that the uniform DOS at two of three independent molecular sites is crucial to induce superconductivity. Taking the site-dependent DOS as a parameter, we constructed a phase diagram for a superconductor with long-range Coulomb interaction, an -type BEDT-TTF family, and summarized the competition between charge instability and superconductivity.
- Received 8 May 2014
- Revised 13 July 2014
DOI:https://doi.org/10.1103/PhysRevB.90.041107
©2014 American Physical Society