Dynamics of dilute vortices in various high-TC thin films

We study the dynamics of dilute vortices in c-axis oriented Y-123, Hg-, and Tl-1212 thin films, as well as a-axis oriented Hg-1212 thin films. Results on the Hg- and Tl-1212 thin films indicate that dislocation-mediated plastic flux creep of single vortices dominates at low temperatures and fields. As the temperature (or the field) is increased, increasing vortex–vortex interactions promote a collective behavior, characterized by elastic creep with a nonzero μ exponent. In some samples, effects of thermally assisted quantum creep are visible up to 45 K. In Y-123 thin films, creep is collective down to the lowest temperatures and fields investigated, while quantum creep persists up to 10–11 K.

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