STRONG-PINNING EFFECTS IN LOW-TEMPERATURE CREEP - CHARGE-DENSITY WAVES IN TAS3

Nonlinear conduction in the quasi-one-dimensional conductor o-TaS3 has been studied in the low-temperature region down to 30 mK. It was foun d that at temperatures below a few degrees Kelvin the current-voltage (I-V) characteristics consist of several branches. The temperature evo lution of the I-V curve proceeds through sequential freezing-out of th e branches. The origin of each branch is attributed to a particular st rong-pinning impurity type. Similar behavior is expected for other phy sical systems with collective transport (spin-density waves, Wigner cr ystals, vortex lattices in type-II superconductors, etc.) in the prese nce of strong-pinning centers.