Fractals, Vol. 14, No. 2 (2006) 125–131 c  World Scientific Publishing Company CHARACTERIZATION OF CHAOTICITY IN THE TRANSIENT CURRENT THROUGH PMMA THIN FILMS A. HACINLIYAN, *,§ Y. SKARLATOS, ‡ H. A. YILDIRIM ‡ and G. SAHIN †,‡ * Departments of Physics and † MIS, Yeditepe University Kayisdagi Caddesi, 34755 Kadikoy, Istanbul, Turkey ‡ Department of Physics, Bogazici University 34342 Bebek, Istanbul, Turkey § avadis@boun.edu.tr Received July 7, 2005 Accepted December 14, 2005 Abstract Chaotic behavior in the transient current through thin Aluminum-PMMA-Aluminum films has been analyzed for times ranging up to 30,000 s, in the temperature range 293–363 K for applied voltages in the range 10–80 V. Time series analysis reveals a positive Lyapunov exponent consistently and reproducibly throughout this range. Power law relaxation as reflected by the autocorrelation function and the positive Lyapunov exponent show parallel behaviors as a function of applied electric field. Keywords : Chaos; Polymer; Conductivity; Lyapunov Exponents. 1. INTRODUCTION This work is a continuation of an earlier report on chaoticity in the transient current through aluminum-polymethylmethacrylate-aluminum thin films. 1 Polymethylmethacrylate (referred to as PMMA in the rest of this work), with the formula [–CH 2 –(CH 3 )C(COOCH 3 )–] n is a polymer whose dielectric behavior has been studied. 2,3 Data were taken according to the two standards ASTM-D257 and IEC93; both methods involve applying a poten- tial difference between the two sides of a planar sam- ple of dielectric and measuring the current flow. 4 This work continues the earlier report on signs of chaotic behavior observed in the time dependent, 125