Edge reconstruction in the ν=2/3 fractional quantum Hall state.

The edge structure of the ν=2/3 fractional quantum Hall state has been studied for several decades, but recent experiments, exhibiting upstream neutral mode(s), a plateau at a Hall conductance of 1/3(e2/h) through a quantum point contact, and a crossover of the effective charge, from e/3 at high temperature to 2e/3 at low temperature, could not be explained by a single theory. Here we develop such a theory, based on edge reconstruction due to a confining potential with finite slope, that admits an additional ν=1/3 incompressible strip near the edge. Renormalization group analysis of the effective edge theory due to disorder and interactions explains the experimental observations.