Effect of a guiding electric field on the melting of a 2D electron crystal above liquid helium

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The conductivity of a two-dimensional electron system with surface density 8⋅108cm−2 and 12⋅108cm−2 above a liquid-helium surface is investigated near a phase transition into the crystalline state (Wigner crystal). The measurements are performed in the frequency range 3–6MHz for different amplitudes of a guiding field. The phase transition was detected according to a sharp change of the amplitude and phase of the response signal. The temperature dependences of the real and imaginary components of the conductivity of two-dimensional system of electrons and the melting temperature are calculated. It is found that the temperature dependences of the imaginary part of the reciprocal of the conductivity, which reflect the inertial properties of the electron system, match well for different frequencies of the exciting signal, while the real component, which characterizes dissipation, increases with increasing frequency at the transition into an ordered state. It is found that at the transition into an ordered state both components of the reciprocal of the conductivity increase with increasing guiding electric field.