Coexistence of the Upper Charge-Density-Wave and the Superconductivity in NbSe₃

Abstract

We have extensively measured the resistance of NbSe 3 near critical pressure ( P 1 = 3.2 GPa) for the upper charge-density-wave ( T 1 -CDW) phase. We reveal that the T 1 -CDW coexists with the superconducting (SC) phase between 2.0 GPa and 2.9 GPa. Near P 1 on the T 1 -CDW side, the T 1 -CDW transition temperature appears to be singularly, T 1 ∼( P 1 - P ) 0.49±0.03 and the SC transition is very broad and becomes much sharpened with increasing pressure. We discuss mechanism of the coexistence of the T 1 -CDW and the SC phase.