We report a systematic experimental study of the anomalous nonlinear magnetotransport in the Wigner solid (WS) trapped on a liquid 4He surface. The ac Corbino conductivity σxx exhibits an abrupt jump at a certain driving voltage. The threshold input voltage Vth for the σxx jump varies as Vth ∝ B-0.8ω-1ns1.5E ⊥, where B, ω, ns, and E⊥ are magnetic field, frequency, electron density and pressing electric field, respectively. We interpret the σxx jump as the transition between the WS accompanied with the periodic 4He 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 behaviors of Vth. We have found that the dependences of σxx on B and E⊥ are different from those of the liquid phase. The anomalous behaviors of σxx play a crucial role on the sliding model.
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