Sliding wigner solid on liquid He-4

We report a systematic experimental study of the anomalous nonlinear magnetotransport in the Wigner solid (WS) trapped on a liquid He-4 surface. The ac Corbino conductivity sigma(xx) exhibits an abrupt jump at a certain driving voltage. The threshold input voltage V-th for the sigma(xx) jump varies as V(th)proportional to B(-0.8)omega(-1)n(s)(1.5)E(perpendicular to), where B, omega, n(s), and E(perpendicular to) are magnetic field, frequency, electron density and pressing electric field, respectively. We interpret the sigma(xx) jump as the transition between the WS accompanied with the periodic He-4 surface deformation and the WS which decouples from the surface, due to the large driving force. A simple model is presented: The rigid-potential sliding model qualitatively explains the above mentioned behaviours of V-th. We have found the dependencies of sigma(xx) on B and E(perpendicular to) are different from those of the liquid phase. The anomalous behaviours of sigma(xx) play a crucial role on the sliding model.