IMPURITY EFFECTS ON CHIRAL ONE-DIMENSIONAL ELECTRON-SYSTEMS

We studied low-energy effects of impurities in several chiral one-dimensional (1D) electron systems that contain only excitations moving in one direction. We first considered single-impurity scattering between two branches of 1D chiral Luttinger liquids. The general form of the impurity-scattering matrix was found which, sometimes, allows the chemical potentials on the outgoing branches to be higher (or lower) than the maximum (or minimum) chemical potentials on the incoming branches. We also studied the effects of many impurities (with finite density) on two branches of 1D chiral Fermi liquids (that appear on the edge of the nu = 2 integral quantum Hall liquid). We found that the impurities drive the system to a fix point at low energies which has an SU(2) symmetry even when the two branches originally have different velocities. [Note that a clean system is SU(2) symmetric only when the two branches have the same velocity.] The probability distribution and correlation of scattering matrices at different energies are described by universal functions which are calculated exactly for this fixed point.