Hysteresis in the underdamed driven Frenkel-Kontorova model

We study a commensurate chain of atoms subject to a periodic substrate potential, damping, and a thermal bath, and driven by an external dc force. In the underdamped case the average system velocity as a function of adiabatically varying force exhibits hysteresis at nonzero temperatures. The hysteresis exists due to the instability of the driven motion of kinks at high velocities. In the force-decreasing process, the system passes through two regimes: the ''cavity-mode'' regime (a standing wave superimposed on the state of running atoms) and the ''traffic-jam'' regime, where the mobility is due to kink-antikink pairs, the kinks being bunched into compact groups. [S0031-9007(97)0443O-X].