CLASSICAL MESOSCOPIC EFFECT IN THE RESISTANCE OF POINT-CONTACTS

The mesoscopic effect of tile point-contact conductance dependence on spatial distribution of the impurities is theoretically studied. It is shown that the resistance R dependence on the diameter d is determine d not only by the electron mean free path I-i, but also by the average distance between the impurities. In the case of two types of impuriti es with different concentrations the mesoscopic effect is predicted fo r the dirty point-contact (d much greater than l(i)) due to the scatte ring on specific (e.g. magnetic) impurities with low concentration. Su ch contacts were numerically modeled for random distributions of the t wo types of impurities.