HYSTERETIC DEPINNING OF ANISOTROPIC CHARGE-DENSITY WAVES

We investigate the depinning transition in a dirty periodic medium con sidering a model of layered charge density waves asa prototype system. We find that depinning from strong disorder occurs via a two stage pr ocess where, first, the pinned system experiences a continuous transit ion into a plastically sliding state and undergoes a second sharp hyst eretic transition into a coherently moving 3D state at In the weakly d isordered system the depinning into a coherently sliding state remains higher drives; continuous.