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arXiv · 1008.4723

Pinning of spiral fluxons by giant screw dislocations in YBa_2Cu_3O_7 single crystals: Josephson analog of the fishtail effect

S. Sergeenkov·L. Jr. Cichetto·V. A. G. Rivera·C. Stari·E. Marega·C. A. Cardoso·F. M. Araujo-Moreira
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Abstract

By using a highly sensitive homemade AC magnetic susceptibility technique, the magnetic flux penetration has been measured in YBa_2Cu_3O_7 single crystals with giant screw dislocations (having the structure of the Archimedean spirals) exhibiting a=3 spiral turnings, the pitch b=18.7 microns and the step height c=1.2nm (the last parameter is responsible for creation of extended weak-link structure around the giant defects). The magnetic field applied parallel to the surface enters winding around the weak-link regions of the screw in the form of the so-called spiral Josephson fluxons characterized by the temperature dependent pitch b_f(T). For a given temperature, a stabilization of the fluxon structure occurs when b_f(T) matches b (meaning an optimal pinning by the screw dislocations) and manifests itself as a pronounced low-field peak in the dependence of the susceptibility on magnetic field (applied normally to the surface) in the form resembling the high-field (Abrikosov) fishtail effect.

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S. Sergeenkov, L. Jr. Cichetto, V. A. G. Rivera, C. Stari, E. Marega, C. A. Cardoso, F. M. Araujo-Moreira. 2010-08-27. Pinning of spiral fluxons by giant screw dislocations in YBa_2Cu_3O_7 single crystals: Josephson analog of the fishtail effect. https://doi.org/10.1134/s0021364010010078

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