Sliding of the wigner solid from the coupled plasmon-ripplon surface deformation

The Wigner solid (WS) on a liquid⁴He surface is accompanied with the periodic surface deformation, i.e. the ripplons whose wavevectors equal the reciprocal WS lattice vectors. This unique situation plays a crucial role in the dynamics of the WS. We have performed an extensive measurement of the ac Corbino conductivity _xx. The WS conductivity shows extremely nonlinear behavior, and it jumps abruptly at a certain input voltage. The threshold input voltage V_th varies as V_thB^–0.8f^–1n_s ^1.5E, where B, f, n_s, and E are magnetic field, frequency, electron density and pressing electric field, respectively. We have interpreted the _xx jump as the collective sliding of the electrons out of the surface deformation.