CLASSICAL MESOSCOPIC EFFECT IN THE RESISTANCE OF POINT CONTACTS

The mesoscopic effect of the dependence of the point-contact conductan ce on the spatial distribution of the impurities is theoretically stud ied. It is shown that the resistance dependence on the diameter d is n ot only determined by the electron mean free path l(i), but also by th e average distance between the impurities. In the case of two types of impurities with different concentrations the mesoscopic effect is pre dicted for a dirty point contact (d much greater than l(i)) due to the scattering at specific (e.g., magnetic) impurities with a low concent ration. Such contacts were numerically modeled for random distribution s of the two types of impurities. (C) 1997 American Institute of Physi cs. [S1063-777X(97)00812-8].