Features of the conductivity of a 2D electron crystal over liquid helium at high driving fields

Abstract

An electron crystal with a surface electron density ns=6.2×108cm−2 over the surface of superfluid liquid helium is investigated as a function of the amplitude of an ac electric field (1–30mV∕cm) in the plane of the layer at a temperature T=80mK. The frequency dependence of the response of the experimental cell to an ac voltage is measured at frequencies where coupled electron-ripplon resonances are excited (1–20MHz), and the dependence of the conductivity of an electron layer on the driving field at two fixed frequencies, 4 and 5MHz, is investigated. A complex nonmonotonic dependence of the conductivity of the crystal on the driving field is observed, which apparently reflects a dynamic phase transition in the system.