Characterization of Lateral Junctions and Micro-SQUIDs Involving Magnetic Multilayers

We have fabricated and characterized at low temperatures Nb/Ni/(Al/Ni)14/Nb lateral junctions and Nb micro-SQUIDs involving (Al/Py)10 multilayers (here Py is permalloy: 80% Ni-20% Fe). We have studied I-V curves and Josephson critical current as a function of an external magnetic field (Ic(H)) at various temperatures and orientations of the applied magnetic field. These studies revealed that, for some orientations of the externally applied magnetic field, the Ic(H) dependence of the lateral junctions has a component highly sensitive to magnetic field. In addition, we have observed a SQUID-like Ic(H) dependence for devices, in which an orthogonally oriented (with respect to the substrate) Nb loop that includes two nanoscopic Josephson junctions is filled with a (Al/Py)10 multilayer. We believe the devices presented here are promising as magnetic field sensors on nanoscale for various applications where high spatial resolution is required.