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arXiv · 0910.4506

New aspects of microwave properties of Nb in the mixed state

N. Pompeo·E. Silva·S. Sarti·C. Attanasio·C. Cirillo
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Abstract

We present a study of the frequency dependence of the vortex dynamics in a conventional superconductor. We have employed a swept-frequency, Corbino-disk technique to investigate the temperature (3.6K-Tc) and high-field (from Hc2/2 to Hc2) microwave complex resistivity in Nb thin (20-40 nm) films as a function of the frequency (1-20 GHz). We have found several previously unnoticed features: (i) a field-dependent depinning frequency in the GHz range; (ii) deviations from the accepted frequency dependence, that can be ascribed to some kind of vortex creep; (iii) the presence of switching phenomena, reminiscent of vortex instabilities. We discuss the possible origin of the features here reported.

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N. Pompeo, E. Silva, S. Sarti, C. Attanasio, C. Cirillo. 2009-10-23. New aspects of microwave properties of Nb in the mixed state. https://doi.org/10.1016/j.physc.2010.02.063

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