Coexistence of different superconducting phases with transition temperatures between 1.5 and 7 K in the (BEDT-TTF)-I-3 system

Two superconducting phases can be identified in the (BEDT-TTF)-I-3 system; the transition temperature for the first phase is T/sub c/ = 1.5 K, while T/sub c/ varies between 2 and 3.3 K for the second phase, depending on the crystal. Appreciable variations in composition are typical for crystals of both phases. The small amount of the second phase present in crystals in the first phase causes the resistance to drop for Troughly-equal 4 K, i.e., prior to the start of the transition itself. In addition, pretransition phenomena beginning at T = 7--8 K are observed for crystals of both phases. These may be attributed to the existence of another superconducting phase in (BEDT-TTF)-I-3 with T/sub c/roughly-equal7 K