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Supercurrent decay measurements of nano-superconducting quantum interference devices (SQUIDs) based on niobium constrictions (Dayem bridges) are reported. Such measurements provide useful information for applications that employ the SQUID as a trigger where the sensor works on the zero voltage state. The nanodevice consists of a niobium thin film (30 nm thick) ring with a hole side length of 200 nm including two Dayem bridges of 120×200 nm2. The measurements of the switching current distribution from the zero voltage state and the related escape rate, as function of the bias current, have been performed by a low noise fly time technique. The experimental data have shown an intrinsic current fluctuation less than 0.2% of the critical current at liquid helium temperature, corresponding to an intrinsic sensor magnetic flux resolution of a few mΦ0. The theoretical predictions based on the thermal escape …
AIP Publishing
Publication date: 
9 Feb 2009

C Granata, A Vettoliere, R Russo, E Esposito, M Russo, B Ruggiero

Biblio References: 
Volume: 94 Issue: 6 Pages: 062503
Applied Physics Letters