Nonlinear dynamics and possible chaoticity in condensed matter systems

Possible chaotic behavior in the transient current through a sample of As2S3(Ag) and As2Se3(Al) thin films was examined with time series analysis, rescaled range (R/S) analysis and q-Gaussian analysis. R/S analysis shows that there are two regimes of fractal behavior; one seems like because of short time scale relaxation and the other one seems like because of long term chaotic behavior. The mutual information data indicate the necessity of noise reduction using a moving average. Extending the moving average window gives correspondingly large delay times as expected. The indicated delay time starts at 20s and grows up to 250s. The false nearest neighbor results also indicate a value around 10. A robust increase in the Lyapunov exponent stretching graphs confirms long term chaos; the result is not sensitive to the precise values of the delay time and embedding dimension. In the q-Gaussian analysis, the fitted long tailed and peaked q-Gaussian curves are completely different from a normal Gaussian. q values greater than one show that the results are consistent with the chaos analysis results.