2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/95462We find mode-locking steps in simulated current-voltage characteristics of ac-driven vortex lattices with {\it random} pinning. For low frequencies there is mode-locking above a finite ac force amplitude, while for large frequencies there is mode-locking for any small ac force. This is correlated with the nature of temporal order in the different regimes in the absence of ac drive. The mode-locked state is a frozen solid pinned in the moving reference of frame, and the depinning from the step shows plastic flow and hysteresis.4 pages, 4 figuresSuperconductivitySoft Condensed Mattertext