Chaotic structures in conductivity mechanisms

Abstract

Chaotic behavior in the transient current through thin Aluminum-PMMA-Alu-minum films has been analyzed for times ranging up to 30000s, in the temperaturerange 293-363 K for applied voltages in the range 10-80V. The general shape of the data suggests a slow decay to a steady state value superimposed with broadband os-cillations. The aperiodic and broadband behavior of the transient current remindsone of an underlying chaotic structure. Indeed time series analysis reveals a positiveLiapunov exponent consistently and reproducibly throughout this range which give sstrong evidence for chaoticity. Power law relaxation as refiected by the autocorrelationfunction and the positive Liapunov exponent show parallel behaviors as a function ofapplied electric field and temperature. The stretched exponential behavior of the data suggests that the process can beseen as random walk between random sites. The qualitative behavior of the data canbe understood in terms of a quenched disorder picture as first suggested by Erzan et.al.