DEPINNING, DEFECT CREATION AND QUANTUM TUNNELING

We study a mechanism of depinning of an electron crystal via generatio n and separation of a dislocation pair. A depinning electric field of the same order of magnitude as the experimental result is found. This depinning electric field is smaller by three orders of magnitude than the potential barrier set by the pinning frequency. In the low impurit y density limit the depinning field is proportional to the square root of the dopant density and the 1.5 power of the dislocation energy. Th e 1.5 power functional dependence has been observed experimentally. Ou r mechanism can be viewed as a convenient way to describe collective q uantum many body tunnelling.