Bifurcations of the Creation of Low-Temperature Maxima of the Tunneling Conductance of a “Dirty” N–I–N Junction

Abstract

The representation of the tunneling conductance G(T) of the “dirty” (with low concentrations of the same nonmagnetic impurities in the I layer) N–I–N junction (where N is a normal metal and I is an insulator) in the form of a sum of conductances of random quantum jumpers penetrating the disordered I layer is obtained in the low-temperature region. It is shown that the axis of the parameter δ = |e0 − eF| giving the deviation of the energy of e0 the quasi-local electron state on the impurity in the I layer from the Fermi energy of eF the dirty N–I–N junction contains a series of bifurcation points, at the transition through each of which (in the direction of the increase in δ) the number of maxima on the temperature dependence G(T) increases by unity; i.e., a new maximum is “born” on the curve G(T). Numerical estimates are given for the characteristic parameters of dirty N–I–N junctions indicating the possibility of the experimental observation of at least the first of these maxima.