Pinning energy versus order parameter in a charge-density-wave system

We have investigated the effects of pressure on the pinned and sliding charge-density-wave states of ${\mathrm{K}}_{0.3}$ ${\mathrm{MoO}}_3$ at 77 and 4.2 K. The application of hydrostatic pressure suppresses the threshold electric field both for the conventional charge-density-wave conduction and for the low-temperature, abrupt depinning. We show that the change in the pinning energy is due to the decrease of the charge-density-wave order parameter and that the pressure dependence of the threshold field favors weak-pinning theories.