THE EFFECT OF GEOMETRIC SCATTERING ON THE OSCILLATORY MAGNETOCONDUCTANCE IN MULTIPLY CONNECTED DISORDERED MESOSCOPIC RINGS

We present the quantum mechanical calculations on the conductance of a n electron in a quantum waveguide consisting of multiply connected mes oscopic rings with disordered ring-circumferences and the ballistic le ad connections between the rings with the transfer matrix approach. Th e profiles of the conductance as functions of the magnetic flux and of the Fermi wave number of electrons depend on the number of rings as a lso on the geometric configuration of the system, We find that there e xist two kinds of minibands, one originating from the quasi-bound stat es of the rings, i.e. the intrinsic minibands, and the other associate d with the connecting leads between the adjacent rings, which are the extra minibands owing to the interfering waves between the two nodes f ormed at the two ends of each lead. These two kinds of minibands have completely different properties and different responses to external pe rturbation. The conductance spectrum of this system for disordered rin g circumferences, disordered ring intervals and disordered magnetic fl ux is examined in detail. It is found that the decay in the localizati on length substantially depends on the type of disorder, the extent of disorder and the Fermi wave number of electrons. We also present the statistical distribution of conductance fluctuations in this disordere d network structure. It is found that the statistical distribution can be normal or log-normal, depending on the extent of the disorder.