Journal article
Flux noise in ion-implanted nanoSQUIDs
GC Tettamanzi, CI Pakes, SKH Lam, S Prawer
Superconductor Science and Technology | Published : 2009
Abstract
Focused ion-beam (FIB) technology has been used to fabricate miniature Nb DC SQUIDs (superconducting quantum interference devices) which incorporate resistively shunted microbridge junctions and a central loop with a hole diameter ranging from 1058 to 50nm. The smallest device, with a 50nm hole diameter, has a white flux noise level of 2.6νΦ0Hz -1/2 at 104Hz. The scaling of the flux noise properties and focusing effect of the SQUID with the hole size were examined. The observed low frequency flux noises of different devices were compared with the contribution due to the spin fluctuation of defects introduced during FIB processing and of thermally activated flux hopping in the SQUID washer. ©..
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Funding Acknowledgements
This work was supported by the Australian Research Council under the Centres of Excellence scheme. G C Tettamanzi acknowledges the Dutch Foundation for Fundamental Research on Matter (FOM) for financial support. We thank A Potenza for providing sputtered Nb films, C Granata for useful discussion, and C Foley for commenting on the manuscript.