Randomness at the edge: Theory of quantum Hall transport at filling ν=2/3

Current Luttinger liquid edge state theories for filling ν=2/3 predict a nonuniversal Hall conductance, in disagreement with experiment. Upon inclusion of random edge tunneling we find a phase transition into a new disorder-dominated edge phase. An exact solution of the random model in this phase gives a quantized Hall conductance of 2/3 and a neutral mode propagating upstream. The presence of the neutral mode changes the predicted temperature dependence for tunneling through a point contact from ${\mathit{T}}^{2/\nu \mathrm{-}2}$ to ${\mathit{T}}^2$.