On the fundamental difference between the effects of electrical and mechanical vibrations on the dynamics of a charge density wave

The effects of radio-frequency electric and strain fields on the depinning and sliding of a charge density wave in the quasi-one-dimensional conductor TaS$_3$ have been compared. The amplitude dependence of the threshold voltage $V_{\mathrm{t}}$ (zeroth Shapiro step) has been studied for both fields. The threshold voltage Vt decreases with increasing radio-frequency electric field $E_{\mathrm{rf}}$ at increasing rate $|dV_{\mathrm{t}}/E_{\mathrm{rf}}|$, whereas with increasing strain field, the decrease in the threshold voltage $V_{\mathrm{t}}$ is saturated, approaching a constant value. This result indicates a qualitative difference between the mechanisms of influence of the electric and strain fields on the dynamics of the charge density wave and is explained by the modulation of the sliding velocity of the charge density wave and pinning potential in the former and latter cases, respectively. In practice, the result allows one to distinguish the mechanical impact on the dynamics of the charge density wave from the influence of electrical interference at the same frequency.