Investigation of the mobility and current-voltage characteristics of surface electrons in helium

The high-frequency conductivity and current-voltage characteristics of a layer of electrons localized on the surface of liquid helium are investigated in the temperature range 0.4−0.7°K at frequencies 4.7 and 14.7 MHz and in drift fields up to ∼5 mV/cm. It is shown that at low drift fields the mobility of the surface electron layer does not depend on the drift field, but with increasing field it grows and then, passing through a maximum, drops. The dependences obtained are attributed to a gradual heating of the electron system by the drift field and the transition of surface electrons to higher energy levels. The effect mentioned leads to the appearance of features on the current-voltage characteristics which are accompanied by hysteresis in the electric field. Moreover, some other features are observed on the current-voltage curves which characterize the dynamics of the heating of the electron layer.

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