Abstract
A new structure other than ii-phase which shows superconductivity below ∼10.4 K was found in a (BEDT-TTF)2Cu(NCS)2 crystal by using scanning tunneling microscopy (STM). The molecular structure was similar to that of a a-phase of (BEDT-TTF)2Cu(NCS)2, previously reported as a new structure with a metal-insulator phase transition at ∼200 K. Properties of the both phase transi-tions were also observed in respect to the temperature dependence of I-V curves (tunneling current-bias voltage curves) measured on the crystal surface. This supports the fact that a new phase such as the a-phase coexists in the crystal as a mixture with the it-phase.
