Nonlinear transport of the Wigner solid on normal and superfluid 3He surfaces

The two-dimensional Wigner solid (WS) formed on the free surface of liquid helium shows strongly nonlinear transport properties. Here we report on the observation and theoretical analysis of a novel nonlinear transport in the WS on both normal and superfluid 3He surfaces. We have observed a transition from Ohmic to nonlinear transport over a wide temperature range, from 200 μK to 200 mK at low electron velocities. The field-velocity (E−v) characteristics show peculiar nonmonotonic structures. We attribute the nonlinearity to the velocity-induced deformation of the periodic surface displacement due to the extremely strong damping in Fermi liquid 3He. The calculated E−v curves and thresholds are in excellent agreement with experiment.