Homogeneous superconducting state at 8.1 K under ambient pressure in the organic conductor β-(BEDT-TTF)2I3

Abstract

We report the observation of the first narrow and complete superconducting transition yet obtained in β-(BEDT-TTF)2I3 at 8.1 K and ambient pressure after pressurization up to 1.5 kbar and a release of the helium gas pressure at low temperature. We show experimental evidences indicating that the metastable state giving rise to homogeneous superconductivity at ambient pressure is not stable above 250 K.