Distinctive features of the charge density wave collective motion driven by Hall electric field in NbSe3

We present a comparative study of the charge density wave (CDW) sliding at low temperatures in NbSe3 between two configurations: the conventional one with the current applied along the chain axis and that, the CDW being driven by the Hall electric field, with the current applied along micrometer-sized bridge-type structures cut perpendicular to the chain axis. In this Hall bar configuration, nonlinear properties can be easily extended to much lower temperatures. The threshold electric field, Et, for CDW depinning is very sharp and has been measured down to 0.1 mK. It is found that Et becomes temperature independent below T ≈ 4.2 K, which suggests a crossover from thermal fluctuations to a tunneling mechanism for CDW depinning.