Superconductivity at High Pressure in NbSe ₃

Abstract

We have measured the electrical resistivity of NbSe3 between 2 K and room temperature up to a pressure of 7.2 GPa. At P1 = 3.5 GPa we observe the extinction of the high-temperature charge density wave (T1-CDW) and the enhancement of the superconducting critical temperature Tc to 5 K. The logarithmic pressure slopes of T1 (P P1) are found to be practically equal. A similar behaviour had been reported previously at lower pressures for T2 (P < P2) and Tc (P2 < P < P1) in the distorted state. We discuss these results in terms of an anisotropic superconducting state in NbSe3, with different gaps associated with different types of chains.