Detection of the flux dynamical regimes in Bi4O4S3 by multiharmonic AC susceptibility

The temperature dependent first and third harmonics of the AC magnetic susceptibility chi(1,3)(T) have been measured on Bi4O4S3. The chi(1)(T) magnetic response is due to the intergranular contribution with a transition temperature T-c approximate to 4.4 K. The dependencies of the chi(3)(T) on the AC field amplitude and frequency reveal a critical state with the presence of the flux creep and the flux flow regimes. In fact, the field dependencies of the effective activation energy and of the frequency dependent critical current density have been found to be described with power laws characteristic of the collective creep regime involving large flux bundles. (C) 2014 Elsevier B.V. All rights reserved.