Meissner and diamagnetic shielding effects of α-EDT-TTF[Ni(dmit)2]

Meissner and diamagnetic shielding effects were investigated for an organic superconductor, α-EDT-TTF[Ni(dmit)2] (dmit = 4,5-dimercapto-1,3-dithiole-2-thione, EDT-TTF=ethylenedithio-tetrathiafulvalene), under ambient pressure. The onset of the diamagnetic transition occurred at 1.39 K. From the measurements of the Meissner effect, the volume fraction of the superconducting phase was estimated to be more than 62%. From the measurements of the diamagnetic shielding effect, this fraction was estimated to be about 93%. This high level of volume fraction shows that the superconducting phase is the main phase in α-EDT-TTF[Ni(dmit)2].