Fishtail effect studied by ac susceptibility in ErBa2Cu3O7−δ single crystal

Abstract

The second magnetization peak (SMP), also known as the fishtail effect, is studied by a scaling procedure for ac susceptibility measurements. From this scaling law the frequency dependence of the critical current J(ν) and the flux creep exponent n can be determined. A striking correlation between n and the SMP is observed, which indicates a clear change in the rate of flux creep around the peak position. This result points to the relevance of the dynamical contribution for the peak formation. However, we could not observe a transition between two different regimes of vortex motion at the SMP. The dependence of the SMP with sample dimensions is also discussed.

Pinning of spiral fluxons by giant screw dislocations in YBa2Cu3O7 − δ single crystals: Josephson analog of the fishtail effect

“…Probably one of the most intriguing phenomena in the vast area of superconductivity is the so-called fishtail effect (FE) which manifests itself as a maximum in the field dependence of the magnetization. There are many different explanations regarding the existence and evolution of FE (see, e.g., [1,2,3,4,5,6,7,8,9,10,11,12] and further references therein). However, the most plausible scenario so far is based on the oxygen deficiency mediated pinning of Abrikosov vortices in non-stoichiometric materials with the highest possible T C due to a perfect match between a vortex core and a defect size.…”