Charge density wave, superconductivity, and non-metallic behaviour under high pressure in ZrTe$_3$

The charge-density-wave (CDW) order of low-dimensional inorganic conductor ZrTe$_3$ is found to increase with increasing pressure, while the superconductivity with filamentary nature is significantly suppressed. It was evidenced in resistivity measurements under pressure up to 0.8 Cpa. The present results suggest that competition between the superconductivity and the CDW is not simply explained by a nesting effect of the Fermi surface, but other origin is needed. Non-metallic behaviour is also found below 4 K under high pressures above 0.6 Gpa. The relationship between the non-metallic state and the pressure-enhanced CDW is expected, although yet inexplicable