Universal phase diagram of superconductivity and charge density wave versus high hydrostatic pressure in pure and Se-doped 1 T -Ta S2

The coexistence of superconductivity (SC) and charge density waves (CDWs) was investigated for pure and Se-doped 1 T -Ta S₂ via electrical resistivity under hydrostatic pressure. A universal superconducting phase diagram was revealed on the border of CDWs. Unlike isovalent S/Se doping and uniaxial pressure, the application of high hydrostatic pressure suppresses CDW more sensitively and thoroughly with the critical pressures P_c(x ) ∼4.70 -6.55 GPa. A pressure-induced superconducting state coexists with various CDWs, then bulk SC emerges along with the complete collapse of various CDWs. The superconducting transition temperature increases monotonously up to ∼7.3 K at 15 GPa without a domelike shape. The results clarify that the superconducting Cooper pairing is associated with the CDWs' instability near P_c(x ) . Above P_c(x ) , the monotonous increase of T_c is attributed to different evolutions of the electronic structures and phonon vibration spectra under hydrostatic and uniaxial pressures and a further inhibition of undetected CDWs.