Nucleation of domains of inverse polarity is observed in the remanent state of high Tc superconductors using the high-resolution Faraday effect (HRF). The remanent state consists of domains with trapped flux and of domains with opposite polarity, separated from each other by an annihilation zone. It is shown that the stray fields of microstructural defects contribute to the nucleation process. Using the capability of the HRF technique to observe dynamic processes, experimental evidence for the different signs of the vortices is given. The influence of the pinning forces on this behavior is also shown.
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