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Investigation of vortex dynamics in Josephson junction arrays with magnetic flux noise measurements

S. Candia·Ch. Leemann·S. Mouaziz·P. Martinoli
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Abstract

We have measured the magnetic flux noise in a two-dimensional Josephson junction array in nominally zero magnetic field, in the vicinity of the superconducting transition. This transition is of the Berezinski-Kosterlitz-Thouless (BKT) type, driven by the unbinding of thermally excited vortex-antivortex pairs. At temperatures just above the BKT transition temperature $T_{c}$, the flux-noise power spectrum $S(ω)$ is white up to a temperature dependent cross-over frequency $ω_ξ(T)$. We identify $ω_ξ$ with the characteristic time related to the scale at which the cross-over from free vortex response to a response dominated by bound pairs occurs. The signature of free vortices is thus white noise while bound vortex pairs give rise to a $1/ω$ dependence.

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S. Candia, Ch. Leemann, S. Mouaziz, P. Martinoli. 2001-11-12. Investigation of vortex dynamics in Josephson junction arrays with magnetic flux noise measurements. https://doi.org/10.1016/s0921-4534(01)01265-5

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