Observation of the Meissner effect in the high-Tc (pressure-)phase of the organic superconductor β-(BEDT-TTF)2I3

Abstract

It is shown that the recently found superconducting state below 6 K in β-(BEDT-TTF)2I3 under a pressure of 1.5 kbar is diamagnetic and exhibits Meissner effects of up to 24 %, indicating that superconductivity is a true volume effect in these crystals. In contrast, no traces of diamagnetism are found in iodine doped α-(BEDT-TTF)2I3, for which resistively observed superconducting transitions in the vicinity of 3 to 5 K have also been reported.