Effects of uniaxial strain on transport properties of organic conductor α-(BEDT-TTF)2I3 and discovery of superconductivity

We demonstrate that an organic conductor alpha-(BEDT-TTF)(2)I-3 exhibits various types of transport phenomena when compressed along some crystal axes. When the sample is strained along the a-axis, the low-temperature electronic state changes from a charge-ordered insulating state under small strains to a narrow gap semiconductor state under large strains. In between these two states, there appears a superconducting state with a T-c of about 7 K. When compressed along the b-axis, on the other hand, this material behaves as a typical quasi-two-dimensional metal with large Fermi surfaces.