Two superconducting phases in the organic conductor : β-(BEDT-TTF)2I3

Abstract

We have shown the first stabilization of homogeneous superconductivity in the β-phase of (BEDT-TTF)2I3 at high temperature and ambient pressure. We propose that the crystallographic transition occuring at 1 bar is responsible of the striking reduction of Tc if no pressure is applied. However, the phase corresponding to the room temperature structure (called β-H) is the only one giving rise to the high-Tc superconductivity and can be frozen at low temperature and atmospheric pressure after the Orsay process. It is worth noting that organic superconductivity is very sensitive to slight changes of physical parameters.