Sputtered YBCO bicrystal dc-SQUIDS

An analysis of YBa1Cu3O7-delta bicrystal dc-SQUIDs is reported. The devices have been fabricated by de cylindrical magnetron sputtering from a single target. SQUIDs operating at the liquid nitrogen temperature have been obtained employing high-quality films fabricated insitu exhibiting a critical temperature as high as 89-90 K. Two different geometrical configurations for the loop inductance have been investigated. A good control of the transport parameters of the junctions, together with a reasonable correlation between the calculated inductance and the voltage response to an applied magnetic field, have been achieved. A study of the voltage response vs. the applied magnetic field as a function of both temperature and bias current has been carried out. SQUIDs working at temperatures as high as 87 K have been characterized.