A technique had recently been developed for fabricating SNS junctions in thin films, using a focused ion beam. These junctions exhibited strong modulation of the critical current by applied magnetic fields and microwaves. They also exhibited large ICRN products, which exceeded 1mV at 4.2K. SQUIDs with directly coupled pick-up loops were made by using this technique, which exhibited large voltage modulations (175μV at 10K) and a noise which was comparable to HTS SQUIDs.

MgB2 Junctions and SQUIDs Fabricated by Focused Ion Beam. G.Burnell, D.J.Kang, D.A.Ansell, H.N.Lee, S.H.Moon, B.Oh, E.J.Tarte, M.G.Blamire: Superconductor Science and Technology, 2003, 16, 254-9