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, E-t, for CDW depinning is very sharp and has been measured down to 0.1 mK. It is found that E-t becomes temperature independent below T approximate to 4.2 K, which suggests a crossover from thermal fluctuations to a tunneling mechanism for CDW depinning.