SPATIAL-DISTRIBUTION OF CURRENT AND FERMI CARRIERS AROUND LOCALIZED ELASTIC SCATTERERS IN QUANTUM TRANSPORT

The two-dimensional spatial distribution of the current and Fermi carriers around localized elastic scatterers in phase-coherent electron transport has been calculated using a generalized scattering-matrix approach. The distributions show dramatic differences depending on whether the scatterers are attractive (donorlike) or repulsive (acceptorlike). We find that attractive scatterers can produce strong vortices in the current, resulting in localized magnetic moments, while repulsive scatterers produce much weaker vortices and may not produce any at all in quasiballistic transport (few impurities). This is a significant difference between majority-carrier transport (when the scatterers are attractive) and minority-carrier transport (scatterers are repulsive). The vortices are caused by quantum-mechanical interference between scatterers and are accentuated by evanescent modes which have a stronger effect in the case of attractive scatterers owing to the formation of quasidonor states. We also examine the influence of the impurity configuration (positions of the scatterers) on the nature of the vortices.