First vortex entry into a perpendicularly magnetized superconducting thin film

In type-II superconductors, the flux-free state (Meissner state) may be invaded by vortices bearing quantized flux once H is above the lower critical field Hc1. However, the actual first flux penetration does not occur at Hc1 due to the presence of a surface barrier and the fact that the Meissner state may also exist as a metastable state up to a larger (superheating) field. In this work we determine the field for the first vortex penetration in superconductors by directly imaging the first vortex threading a superconducting Pb film with antidots. We find that the first vortex penetration occurs when the surface superconducting currents reach the depairing current, locally breaking superconductivity and allowing a vortex to nucleate.

Publication year:2013

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BOF-publication weight:1

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Authors:International

Authors from:Higher Education

Accessibility:Open