Pressure tuning of the charge density wave and superconductivity in 2 H − TaS 2

Both the vibrational and electrical transport properties of $2H\\text{\\ensuremath{-}}{\\mathrm{TaS}}_{2}$ have been investigated at high pressures and low temperatures. The collapse of the charge-density-wave order at pressures above 7.3 GPa has been verified by Raman scattering, resistivity, and Hall coefficient measurements. For pressures above the critical pressure of 7.3 GPa, the superconducting transition temperature continues to increase and reaches its maximum value at 11.5 GPa, suggesting that it is not a simple competition between the charge-density-wave order and superconductivity. Through the standard resistivity fit in the normal state, the decline of the superconducting transition temperature with increasing pressure up to 47.0 GPa is due to the decrease of interaction strength and the increase of the impurity scattering. These results are very important in understanding the superconducting mechanism of transition-metal dichalcogenides.