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 elect rode on top of the edge channels. Reproducible fluctuations in the coupling are observed and interpreted as a mesoscopic fingerprint of single spin-fl ip scatterers which are turned on and off. A model to analyze macroscopic e dge state coupling in terms of individual scatterers is developed, and char acteristic values for these scatterers in our samples are extracted. For al l samples investigated, the distance between spin-flip scatterers lies betw een the Drude and the quantum scattering length. [S0163-1829(99)12603-1].