MEISSNER AND DIAMAGNETIC SHIELDING EFFECTS OF ALPHA-EDT-TTF[NI(DMIT)(2)]

Meissner and diamagnetic shielding effects were investigated for an or ganic superconductor, alpha-EDT-TTF[Ni(dmit)(2)] (dmit = 4,5-dimercapt o-1,3-dithiole-2-thione, EDT-TTF = ethylenedithio-tetrathiafulvalene), under ambient pressure. The onset of the diamagnetic transition occurr ed at 1.39 K. From the measurements of the Meissner effect, the volume fraction of the superconducting phase was estimated to be more than 6 2%. From the measurements of the diamagnetic shielding effect, this fr action was estimated to be about 93%. This high level of volume fracti on shows that the superconducting phase is the main phase in alpha-EDT -TTF[Ni(dmit)(2)].