Pressure effects on the charge-density-wave phases in2H−TaSe2

The transition temperatures from the commensurate to incommensurate phase ($T_d$) and from the incommensurate to normal phase ($T_0$) in $2H-\mathrm{Ta}{\mathrm{Se}}_2$ have been determined as a function of hydrostatic pressure up to 18 kbar. We found that while $T_0$ increases only slightly with pressure, $T_d$ falls rapidly as ${(1-\frac{P}{P_c})}^{\frac{1}{2}}$ under pressure, extrapolating to a critical pressure $P_c$ of 17 kbar for the complete stabilization of the incommensurate phase. We conclude that the interlayer coupling can not be neglected in discussing the stability of the charge-density-wave state.