Universal dependence on the average conductance of conductance fluctuations in disordered metals.

Abstract

We have computed the amplitude of conductance fluctuations in a variety of disordered two-dimensional mesoscopic systems by evaluating the Kubo-Greenwood formula. Our models range from substitutional binary alloys to topologically disordered ``glasses,'' and include systems where the disorder is caused by the random small displacements of atoms from their positions in a crystalline lattice. As in our previous work, our Hamiltonian is reminiscent of the Kronig-Penney model in that \ensuremath{\delta}-function-like atomic potentials are specified by a single parameter. We study systems whose size is always larger than the elastic mean free path, but which are not always smaller than the localization length for the electrons. We observe evidence that there is a universal relationship between the amplitude of the fluctuations and the value of the conductance itself: This relationship does not depend upon the nature of the disorder.