Individual scatterers as microscopic origin of equilibration between   spin- polarized edge channels in the quantum Hall regime
  The equilibration length between spin-polarized edge states in the Quantum Hall regime is measured as a function of a gate voltage applied to an electrode on top of the edge channels. Reproducible fluctuations in the coupling are observed and interpreted as a mesoscopic fingerprint of single spin-flip scatterers which are turned on and off. A model to analyze macroscopic edge state coupling in terms of individual scatterers is developed, and characteristic values for these scatterers in our samples are extracted. For all samples investigated, the distance between spin-flip scatterers lies between the Drude and the quantum scattering length. 
Y. Acremann, T. Heinzel, and K. Ensslin E. Gini and H. Melchior and M.   Holland