Insulator-conductor behavior of a two-dimensional electron system on a helium film

We performed a Langevin molecular dynamics simulation to study the response of a two-dimensional (2D) constrained electron system on a helium film due to an external force parallel to the surface. The electron drift velocity was obtained as a function of the driven force for different values of film thickness and dielectric constants of the substrate in the low temperature regime (T→0). We observed that the system had undergone an insulator-conductor transition after a finite depinning threshold of the driven force. This should be helpful for understanding the nonlinear dc conductivity observed in 2D systems, such as that in semiconductor heterostructures.