On the theory of electron–ripplon resonances in a two-dimensional Wigner crystal on a liquid-helium surface
Abstract
A theoretical study is made of the structure of resonance anomalies in the high-frequency conductivity of a two-dimensional electron crystal on the free surface of liquid helium in a uniform electric field parallel to the liquid-vapor interface. New mechanisms responsible for these resonances are suggested and analyzed. It is shown that in relatively weak driving fields (of the order of 1 mV/cm) nonlinear effects resulting in additional, low-frequency resonances are significant. Under nonresonance conditions we calculate the concentration and frequency dependence of the conductivity of the two-dimensional Wigner crystal; this can provide interesting information about the character of the dissipative processes near the free surface of liquid helium.