Control of Electronic Properties of Organic Conductors by Hydrostatic and Uniaxial Compression

Abstract

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 cause and enhance superconductivity in two-dimensional organic conductors, α-(BEDT-TTF)2KHg(SCN)4 and its isostructural compound having NH4 instead of K. We found that these two compounds show essentially the same properties if their lattice parameters are appropriately reduced by the uniaxial strain method, although they show quite different properties under ambient and hydrostatic pressures. In the one-dimensional organic superconductor (TMTSF)2PF6, we found a novel result that is contradictory to the current interpretation for the suppression of spin density waves under pressures.