Fine optimization of Josephson critical current in SQUID devices by thermal annealing

In the present article an experimental study regarding optimization and fine-tuning and of Superconducting QUantum Interference Device (SQUID) parameters by a thermal annealing is presented. It allows to modify the parameters in order to meet a specific application or to adjust the device parameters to reduce the magnetic field noise preventing the work instability conditions due to a critical current value that exceed the expected one. In particular, we carried out the measurements of the critical current and the voltage swing as a functions of the annealing temperatures or time showing the effect of such procedures on the magnetic field spectral density of the SQUID magnetometers The experimental results demonstrate that it is possible to optimize the main device parameters reducing the SQUID noise to a suitable value improving the stability of working operations.