EDGE MELTING AND COLLECTIVE EDGE EXCITATIONS OF THE 2-DIMENSIONAL WIGNER CRYSTAL IN A STRONG MAGNETIC-FIELD

The edge electronic structure and collective excitations of a two-dime nsional Wigner crystal are studied as a function of the strength of an external static potential that compresses the electrons at the edge o f the crystal. It is demonstrated that, as the strength of the externa l confining potential is increased, the electrons at the edge may melt , giving rise to a phase of the two-dimensional electron gas in which the bulk is essentially crystalline, while the edge is melted. In the generalized random-phase approximation, this melting transition is sig naled by the appearance of a collective mode which is gapless even in the presence of pinning centers, and is localized to the edge of the s ystem. The consequences of this melting transition on the transport pr operties of the system are discussed.