Tuning the correlation decay in the resistance fluctuations of multi-species networks

Abstract

A new network model is proposed for describing the1/fα resistance noise in disordered materials for a wide range ofα values (0<α<2). More precisely, we have considered the resistance fluctuations of a thin resistor withgranular structure in different stationary states: from nearly equilibrium to far fromequilibrium conditions. This system has been modeled as a network made up ofdifferent species of resistors, distinguished by their resistances, by their temperaturecoefficients and by the energies associated with thermally activated processes ofbreaking and recovery. The correlation behavior of the resistance fluctuationsis analyzed as a function of the temperature and applied current, in both thefrequency and time domains. For the noise frequency exponent, the model provides0<α<1 at low currents, in theohmic regime, with α decreasing inversely with the temperature, and1<α<2 at high currents, in the non-ohmic regime. Since the threshold currentassociated with the onset of non-linearity also depends on the temperature,the proposed model qualitatively accounts for the complicated behavior ofα versus temperature and current observed in many experiments. Correspondingly, in thetime domain, the auto-correlation function of the resistance fluctuations displays a varietyof behaviors which are tuned by the external conditions.