Dynamical defects in two-dimensional Wigner crystal: Self-doping and kinetic magnetism

The two-dimensional Wigner crystal (WC) occurs in the strong interaction regime of a two-dimensional electron gas (2DEG). I will talk about the quantum dynamics of point defects (interstitials and vacancies) in a WC and its possible consequences on the 2DEG phases. First, the energetics of the defects are studied using the semi-classical instanton method that is asymptotically exact at low density, i.e., in the r_s →∞ limit. The resulting semi-classical expression for the interstitial energy vanishes at r_s = r_mit ≈ 30, signaling a possible self-doping instability of a WC to a partially melted WC for some range of r_s below r_mit. This suggests the possible existence of a "metallic electron crystal" phase in the two-dimensional electron gas at intermediate densities between a low-density insulating WC and a high-density Fermi fluid. I will also discuss magnetic correlations induced by various dynamical processes of interstitials and vacancies.