Influence of uniaxial strain on the electronic properties of (TMTSF) ₂ReO ₄ compounds

To study the influence of uniaxial strain on anion-orderings and superconductivity, we measured electrical resistance along the a (R _xx) and c*-axes (R _zz) under uniaxial strain on (TMTSF) ₂ReO ₄. Compared to the pressure-temperature phase diagrams under hydrostatic pressure, those under uniaxial strain depend on the direction along which the pressure is applied. The difference is particularly large when the uniaxial strain is applied along the c*-axis. The compression along only one direction diminishes (1/2,1/2,1/2) anion ordering transition similar to those under hydrostatic pressure. On the other hand, (0,1/2,1/2) anion ordering transition is completely suppressed and anomalous behavior which enhances non-metallic ground state is observed when the samples are compressed along the c*-axis. The superconducting transition of TMTSF) ₂ReO ₄ is suppressed in R _zz under pressure along the c*-axis.