Artificial control of intermolecular distance of organic superconductors: α-type BEDT–TTF compounds

We developed the uniaxial strain method to artificially control the electronic properties of organic conductors by reducing the intermolecular distance along a desired direction without changing those along others. Using this method, we were able to induce and enhance the superconductivity in two-dimensional (2D) organic conductors, α-(BEDT–TTF)2KHg(SCN)4 and its iso-structural compound having NH4 instead of K, respectively. We found that these two compounds show essentially the same properties if their lattice parameters are reduced along appropriate directions by the uniaxial strain method, while they show apparently different properties under ambient and hydrostatic pressures.