A nonlinear analysis of the transport Barkhausen-like noise measured in (Bi,Pb)(2)Sr2Ca2Cu3O10+delta superconductors

Chaos Volume: 23 Issue: 2 Published: 2013

Transport Barkhausen-like noise TBN easured in sample BP4 for a normalized excitation current density Jex=Jc(0) = 0.5, where Jc(0) is the critical current density at zero applied magnetic field. The ac triangular applied magnetic field, Ba(t), used in all measurements is also shown in the Figure. △t = ti tf represents the time width in which the TBN signal occurs

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Writers: Garcia-Fornaris, I. ; Millan, H. ; Jardim, R. F.,  Govea-Alcaide

Keywords: superconductors;

Abstract: We investigated the transport Barkhausen-like noise (TBN) by using nonlinear time series analysis. TBN signals were measured in (Bi,Pb)2Sr2Ca2Cu3O10+δ ceramic samples subjected to different uniaxial compacting pressures (UCP). These samples display similar intragranular properties but different intergranular features. We found positive Lyapunov exponents in all samples, λm0.062λm≥0.062, indicating the nonlinear dynamics of the experimental TBN signals. It was also observed higher values of the embedding dimension, m>9m>9, and the Kaplan-Yorke dimension, DKY>2.9DKY>2.9. Between samples, the behavior of λmλm and DKY with increasing excitation current is quite different. Such a behavior is explained in terms of changes in the microstructure associated with the UCP. In addition, determinism tests indicated that the TBN masked determinist components, as inferred by |||k||||k→| values larger than 0.70 in most of the cases. Evidence on the existence of empirical attractors by reconstructing the phase spaces has been also found. All obtained results are useful indicators of the interplay between the uniaxial compacting pressure, differences in the microstructure of the samples, and the TBN signal dynamics.

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