HALL-VELOCITY LIMITED MAGNETOCONDUCTIVITY IN A 2D WIGNER SOLID

The magnetoconductivity sigma(B) of a classical 2D electron crystal on superfluid He-4 is non-linear. Experimentally we find a contribution to sigma(B) which, at constant field, gives sigma(B) proportional to J (x), the current density, while at constant current, sigma(B) proporti onal to 1/B. In this region the Hall velocity v(H) slowly approaches t he ripplon velocity v(1) at the first reciprocal lattice vector, due t o strong electron-ripplon interactions with the helium. The magnetocon ductivity decreases sharply for v(H) > v(1). Fluctuations in sigma(B) are seen above the melting temperature.