Effects of Uniaxial Strain on Transport Properties of Organic Conductor α-(BEDT-TTF)₂I₃ and Discovery of Superconductivity

Abstract

We demonstrate that an organic conductor α-(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.